Skip to content
BranchesTags

Repository files navigation

Hooks / Optimization Roundtable

Takeaways:

Memoization

Memoization is an optimization technique, used primarily to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again.

useEffect

  • Used to perform side effects / react to changes in variables
  • By default runs every render, unless an array of dependencies is provided

useCallback

  • Returns a memoized callback.

useMemo

  • Returns a memoized value.
  • Only recomputes value when dependencies change.
  • Can be used to stablize unstable inputs, to avoid unncessarily re-computer complex logic
  • Not the place for side effects. Those go in useEffect.
  • By default runs every render, unless an array of dependencies is provided

Hook dependencies

  • Some hooks take an array of dependencies are compared based on reference or value (for primitive types). So it you pass in an object/array/function that does not have a stable reference, useEffect will run a lot. Don't do that!
  • Make sure to add airbnb/hooks to your eslint to see warnings about missing or unstable dependencies

React.memo

  • React.memo is a higher order component
  • Components will rerender when their parents re-render, even it there props don't change. You can avoid this by wrapping your child component in memo(). It iwll only rerener when internal state/hooks/context changes, and when its props change.

Vaguely Related: Redux Selectors

  • useSelector from redux uses similar logic for dependencies So that is also a scenario you want to be careful of returning new objects vs references to existing ones.

  • More info

  • By creating into a new object/reference it will always return a new object. Therefore your component will re-render on every action that gets dispatched (not just ones that meaningfully change the value of the selector) e.g.

// good stuff, returning existing reference
const user = useSelector(state => state.users);
// bad! new reference
const user = useSelector(state => state.users.map(user=>user.name));

eslint extends airbnb/hooks

Getting Started with Create React App

This project was bootstrapped with Create React App.

Available Scripts

In the project directory, you can run:

npm start

Runs the app in the development mode.
Open http://localhost:3000 to view it in the browser.

The page will reload if you make edits.
You will also see any lint errors in the console.

npm test

Launches the test runner in the interactive watch mode.
See the section about running tests for more information.

npm run build

Builds the app for production to the build folder.
It correctly bundles React in production mode and optimizes the build for the best performance.

The build is minified and the filenames include the hashes.
Your app is ready to be deployed!

See the section about deployment for more information.

npm run eject

Note: this is a one-way operation. Once you eject, you can’t go back!

If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.

Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.

You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.

Learn More

You can learn more in the Create React App documentation.

To learn React, check out the React documentation.

Code Splitting

This section has moved here: https://facebook.github.io/create-react-app/docs/code-splitting

Analyzing the Bundle Size

This section has moved here: https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size

Making a Progressive Web App

This section has moved here: https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app

Advanced Configuration

This section has moved here: https://facebook.github.io/create-react-app/docs/advanced-configuration

Deployment

This section has moved here: https://facebook.github.io/create-react-app/docs/deployment

npm run build fails to minify

This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify

About

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Resources

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, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
 blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
GitHub - kaplantm/hook-optimization · GitHub
Skip to content
BranchesTags
Repository files navigation
Hooks / Optimization Roundtable
Takeaways:
Memoization
Memoization is an optimization technique, used primarily to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again.
useEffect
  • Used to perform side effects / react to changes in variables
  • By default runs every render, unless an array of dependencies is provided
useCallback
  • Returns a memoized callback.
useMemo
  • Returns a memoized value.
  • Only recomputes value when dependencies change.
  • Can be used to stablize unstable inputs, to avoid unncessarily re-computer complex logic
  • Not the place for side effects. Those go in useEffect.
  • By default runs every render, unless an array of dependencies is provided
Hook dependencies
  • Some hooks take an array of dependencies are compared based on reference or value (for primitive types). So it you pass in an object/array/function that does not have a stable reference, useEffect will run a lot. Don't do that!
  • Make sure to add airbnb/hooks to your eslint to see warnings about missing or unstable dependencies
React.memo
  • React.memo is a higher order component
  • Components will rerender when their parents re-render, even it there props don't change. You can avoid this by wrapping your child component in memo(). It iwll only rerener when internal state/hooks/context changes, and when its props change.
Vaguely Related: Redux Selectors
  • useSelector from redux uses similar logic for dependencies So that is also a scenario you want to be careful of returning new objects vs references to existing ones.
  • More info
  • By creating into a new object/reference it will always return a new object. Therefore your component will re-render on every action that gets dispatched (not just ones that meaningfully change the value of the selector)
e.g.
// good stuff, returning existing reference
const user = useSelector(state => state.users);
// bad! new reference
const user = useSelector(state => state.users.map(user=>user.name));

eslint extends airbnb/hooks
Getting Started with Create React App
This project was bootstrapped with Create React App.
Available Scripts
In the project directory, you can run:
npm start
Runs the app in the development mode.

Open http://localhost:3000 to view it in the browser.
The page will reload if you make edits.

You will also see any lint errors in the console.
npm test
Launches the test runner in the interactive watch mode.

See the section about running tests for more information.
npm run build
Builds the app for production to the build folder.

It correctly bundles React in production mode and optimizes the build for the best performance.
The build is minified and the filenames include the hashes.

Your app is ready to be deployed!
See the section about deployment for more information.
npm run eject
Note: this is a one-way operation. Once you eject, you can’t go back!
If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.
Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.
You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.
Learn More
You can learn more in the Create React App documentation.
To learn React, check out the React documentation.
Code Splitting
This section has moved here: https://facebook.github.io/create-react-app/docs/code-splitting
Analyzing the Bundle Size
This section has moved here: https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size
Making a Progressive Web App
This section has moved here: https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app
Advanced Configuration
This section has moved here: https://facebook.github.io/create-react-app/docs/advanced-configuration
Deployment
This section has moved here: https://facebook.github.io/create-react-app/docs/deployment
npm run build fails to minify
This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify
About
No description, website, or topics provided.
Resources
Readme
Activity
Stars
1 star
Watchers
1 watching
Forks
0 forks
Report repository
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
.markdown-body blockquote { border-left-color: #8b949e; }
.markdown-body hr { border-color: #30363d; }
';
document.head.appendChild(style);
})();
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
GitHub - kaplantm/hook-optimization · GitHub
Skip to content
BranchesTags
Repository files navigation
Hooks / Optimization Roundtable
Takeaways:
Memoization
Memoization is an optimization technique, used primarily to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again.
useEffect
  • Used to perform side effects / react to changes in variables
  • By default runs every render, unless an array of dependencies is provided
useCallback
  • Returns a memoized callback.
useMemo
  • Returns a memoized value.
  • Only recomputes value when dependencies change.
  • Can be used to stablize unstable inputs, to avoid unncessarily re-computer complex logic
  • Not the place for side effects. Those go in useEffect.
  • By default runs every render, unless an array of dependencies is provided
Hook dependencies
  • Some hooks take an array of dependencies are compared based on reference or value (for primitive types). So it you pass in an object/array/function that does not have a stable reference, useEffect will run a lot. Don't do that!
  • Make sure to add airbnb/hooks to your eslint to see warnings about missing or unstable dependencies
React.memo
  • React.memo is a higher order component
  • Components will rerender when their parents re-render, even it there props don't change. You can avoid this by wrapping your child component in memo(). It iwll only rerener when internal state/hooks/context changes, and when its props change.
Vaguely Related: Redux Selectors
  • useSelector from redux uses similar logic for dependencies So that is also a scenario you want to be careful of returning new objects vs references to existing ones.
  • More info
  • By creating into a new object/reference it will always return a new object. Therefore your component will re-render on every action that gets dispatched (not just ones that meaningfully change the value of the selector)
e.g.
// good stuff, returning existing reference
const user = useSelector(state => state.users);
// bad! new reference
const user = useSelector(state => state.users.map(user=>user.name));

eslint extends airbnb/hooks
Getting Started with Create React App
This project was bootstrapped with Create React App.
Available Scripts
In the project directory, you can run:
npm start
Runs the app in the development mode.

Open http://localhost:3000 to view it in the browser.
The page will reload if you make edits.

You will also see any lint errors in the console.
npm test
Launches the test runner in the interactive watch mode.

See the section about running tests for more information.
npm run build
Builds the app for production to the build folder.

It correctly bundles React in production mode and optimizes the build for the best performance.
The build is minified and the filenames include the hashes.

Your app is ready to be deployed!
See the section about deployment for more information.
npm run eject
Note: this is a one-way operation. Once you eject, you can’t go back!
If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.
Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.
You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.
Learn More
You can learn more in the Create React App documentation.
To learn React, check out the React documentation.
Code Splitting
This section has moved here: https://facebook.github.io/create-react-app/docs/code-splitting
Analyzing the Bundle Size
This section has moved here: https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size
Making a Progressive Web App
This section has moved here: https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app
Advanced Configuration
This section has moved here: https://facebook.github.io/create-react-app/docs/advanced-configuration
Deployment
This section has moved here: https://facebook.github.io/create-react-app/docs/deployment
npm run build fails to minify
This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify
About
No description, website, or topics provided.
Resources
Readme
Activity
Stars
1 star
Watchers
1 watching
Forks
0 forks
Report repository
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Packages
Contributors
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
GitHub - kaplantm/hook-optimization · GitHub
Skip to content
BranchesTags
Repository files navigation
Hooks / Optimization Roundtable
Takeaways:
Memoization
Memoization is an optimization technique, used primarily to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again.
useEffect
  • Used to perform side effects / react to changes in variables
  • By default runs every render, unless an array of dependencies is provided
useCallback
  • Returns a memoized callback.
useMemo
  • Returns a memoized value.
  • Only recomputes value when dependencies change.
  • Can be used to stablize unstable inputs, to avoid unncessarily re-computer complex logic
  • Not the place for side effects. Those go in useEffect.
  • By default runs every render, unless an array of dependencies is provided
Hook dependencies
  • Some hooks take an array of dependencies are compared based on reference or value (for primitive types). So it you pass in an object/array/function that does not have a stable reference, useEffect will run a lot. Don't do that!
  • Make sure to add airbnb/hooks to your eslint to see warnings about missing or unstable dependencies
React.memo
  • React.memo is a higher order component
  • Components will rerender when their parents re-render, even it there props don't change. You can avoid this by wrapping your child component in memo(). It iwll only rerener when internal state/hooks/context changes, and when its props change.
Vaguely Related: Redux Selectors
  • useSelector from redux uses similar logic for dependencies So that is also a scenario you want to be careful of returning new objects vs references to existing ones.
  • More info
  • By creating into a new object/reference it will always return a new object. Therefore your component will re-render on every action that gets dispatched (not just ones that meaningfully change the value of the selector)
e.g.
// good stuff, returning existing reference
const user = useSelector(state => state.users);
// bad! new reference
const user = useSelector(state => state.users.map(user=>user.name));

eslint extends airbnb/hooks
Getting Started with Create React App
This project was bootstrapped with Create React App.
Available Scripts
In the project directory, you can run:
npm start
Runs the app in the development mode.

Open http://localhost:3000 to view it in the browser.
The page will reload if you make edits.

You will also see any lint errors in the console.
npm test
Launches the test runner in the interactive watch mode.

See the section about running tests for more information.
npm run build
Builds the app for production to the build folder.

It correctly bundles React in production mode and optimizes the build for the best performance.
The build is minified and the filenames include the hashes.

Your app is ready to be deployed!
See the section about deployment for more information.
npm run eject
Note: this is a one-way operation. Once you eject, you can’t go back!
If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.
Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.
You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.
Learn More
You can learn more in the Create React App documentation.
To learn React, check out the React documentation.
Code Splitting
This section has moved here: https://facebook.github.io/create-react-app/docs/code-splitting
Analyzing the Bundle Size
This section has moved here: https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size
Making a Progressive Web App
This section has moved here: https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app
Advanced Configuration
This section has moved here: https://facebook.github.io/create-react-app/docs/advanced-configuration
Deployment
This section has moved here: https://facebook.github.io/create-react-app/docs/deployment
npm run build fails to minify
This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify
About
No description, website, or topics provided.
Resources
Readme
Activity
Stars
1 star
Watchers
1 watching
Forks
0 forks
Report repository
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Packages
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
GitHub - kaplantm/hook-optimization · GitHub
Skip to content
BranchesTags
Repository files navigation
Hooks / Optimization Roundtable
Takeaways:
Memoization
Memoization is an optimization technique, used primarily to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again.
useEffect
  • Used to perform side effects / react to changes in variables
  • By default runs every render, unless an array of dependencies is provided
useCallback
  • Returns a memoized callback.
useMemo
  • Returns a memoized value.
  • Only recomputes value when dependencies change.
  • Can be used to stablize unstable inputs, to avoid unncessarily re-computer complex logic
  • Not the place for side effects. Those go in useEffect.
  • By default runs every render, unless an array of dependencies is provided
Hook dependencies
  • Some hooks take an array of dependencies are compared based on reference or value (for primitive types). So it you pass in an object/array/function that does not have a stable reference, useEffect will run a lot. Don't do that!
  • Make sure to add airbnb/hooks to your eslint to see warnings about missing or unstable dependencies
React.memo
  • React.memo is a higher order component
  • Components will rerender when their parents re-render, even it there props don't change. You can avoid this by wrapping your child component in memo(). It iwll only rerener when internal state/hooks/context changes, and when its props change.
Vaguely Related: Redux Selectors
  • useSelector from redux uses similar logic for dependencies So that is also a scenario you want to be careful of returning new objects vs references to existing ones.
  • More info
  • By creating into a new object/reference it will always return a new object. Therefore your component will re-render on every action that gets dispatched (not just ones that meaningfully change the value of the selector)
e.g.
// good stuff, returning existing reference
const user = useSelector(state => state.users);
// bad! new reference
const user = useSelector(state => state.users.map(user=>user.name));

eslint extends airbnb/hooks
Getting Started with Create React App
This project was bootstrapped with Create React App.
Available Scripts
In the project directory, you can run:
npm start
Runs the app in the development mode.

Open http://localhost:3000 to view it in the browser.
The page will reload if you make edits.

You will also see any lint errors in the console.
npm test
Launches the test runner in the interactive watch mode.

See the section about running tests for more information.
npm run build
Builds the app for production to the build folder.

It correctly bundles React in production mode and optimizes the build for the best performance.
The build is minified and the filenames include the hashes.

Your app is ready to be deployed!
See the section about deployment for more information.
npm run eject
Note: this is a one-way operation. Once you eject, you can’t go back!
If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.
Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.
You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.
Learn More
You can learn more in the Create React App documentation.
To learn React, check out the React documentation.
Code Splitting
This section has moved here: https://facebook.github.io/create-react-app/docs/code-splitting
Analyzing the Bundle Size
This section has moved here: https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size
Making a Progressive Web App
This section has moved here: https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app
Advanced Configuration
This section has moved here: https://facebook.github.io/create-react-app/docs/advanced-configuration
Deployment
This section has moved here: https://facebook.github.io/create-react-app/docs/deployment
npm run build fails to minify
This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
GitHub - kaplantm/hook-optimization · GitHub
Skip to content
BranchesTags
Repository files navigation
Hooks / Optimization Roundtable
Takeaways:
Memoization
Memoization is an optimization technique, used primarily to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again.
useEffect
  • Used to perform side effects / react to changes in variables
  • By default runs every render, unless an array of dependencies is provided
useCallback
  • Returns a memoized callback.
useMemo
  • Returns a memoized value.
  • Only recomputes value when dependencies change.
  • Can be used to stablize unstable inputs, to avoid unncessarily re-computer complex logic
  • Not the place for side effects. Those go in useEffect.
  • By default runs every render, unless an array of dependencies is provided
Hook dependencies
  • Some hooks take an array of dependencies are compared based on reference or value (for primitive types). So it you pass in an object/array/function that does not have a stable reference, useEffect will run a lot. Don't do that!
  • Make sure to add airbnb/hooks to your eslint to see warnings about missing or unstable dependencies
React.memo
  • React.memo is a higher order component
  • Components will rerender when their parents re-render, even it there props don't change. You can avoid this by wrapping your child component in memo(). It iwll only rerener when internal state/hooks/context changes, and when its props change.
Vaguely Related: Redux Selectors
  • useSelector from redux uses similar logic for dependencies So that is also a scenario you want to be careful of returning new objects vs references to existing ones.
  • More info
  • By creating into a new object/reference it will always return a new object. Therefore your component will re-render on every action that gets dispatched (not just ones that meaningfully change the value of the selector)
e.g.
// good stuff, returning existing reference
const user = useSelector(state => state.users);
// bad! new reference
const user = useSelector(state => state.users.map(user=>user.name));

eslint extends airbnb/hooks
Getting Started with Create React App
This project was bootstrapped with Create React App.
Available Scripts
In the project directory, you can run:
npm start
Runs the app in the development mode.

Open http://localhost:3000 to view it in the browser.
The page will reload if you make edits.

You will also see any lint errors in the console.
npm test
Launches the test runner in the interactive watch mode.

See the section about running tests for more information.
npm run build
Builds the app for production to the build folder.

It correctly bundles React in production mode and optimizes the build for the best performance.
The build is minified and the filenames include the hashes.

Your app is ready to be deployed!
See the section about deployment for more information.
npm run eject
Note: this is a one-way operation. Once you eject, you can’t go back!
If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.
Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.
You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.
Learn More
You can learn more in the Create React App documentation.
To learn React, check out the React documentation.
Code Splitting
This section has moved here: https://facebook.github.io/create-react-app/docs/code-splitting
Analyzing the Bundle Size
This section has moved here: https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size
Making a Progressive Web App
This section has moved here: https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app
Advanced Configuration
This section has moved here: https://facebook.github.io/create-react-app/docs/advanced-configuration
Deployment
This section has moved here: https://facebook.github.io/create-react-app/docs/deployment
npm run build fails to minify
This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify
About
No description, website, or topics provided.
Resources
Readme
Activity
Stars
1 star
Watchers
1 watching
Forks
0 forks
Report repository
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Contributors
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
GitHub - kaplantm/hook-optimization · GitHub
Skip to content
BranchesTags
Repository files navigation
Hooks / Optimization Roundtable
Takeaways:
Memoization
Memoization is an optimization technique, used primarily to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again.
useEffect
  • Used to perform side effects / react to changes in variables
  • By default runs every render, unless an array of dependencies is provided
useCallback
  • Returns a memoized callback.
useMemo
  • Returns a memoized value.
  • Only recomputes value when dependencies change.
  • Can be used to stablize unstable inputs, to avoid unncessarily re-computer complex logic
  • Not the place for side effects. Those go in useEffect.
  • By default runs every render, unless an array of dependencies is provided
Hook dependencies
  • Some hooks take an array of dependencies are compared based on reference or value (for primitive types). So it you pass in an object/array/function that does not have a stable reference, useEffect will run a lot. Don't do that!
  • Make sure to add airbnb/hooks to your eslint to see warnings about missing or unstable dependencies
React.memo
  • React.memo is a higher order component
  • Components will rerender when their parents re-render, even it there props don't change. You can avoid this by wrapping your child component in memo(). It iwll only rerener when internal state/hooks/context changes, and when its props change.
Vaguely Related: Redux Selectors
  • useSelector from redux uses similar logic for dependencies So that is also a scenario you want to be careful of returning new objects vs references to existing ones.
  • More info
  • By creating into a new object/reference it will always return a new object. Therefore your component will re-render on every action that gets dispatched (not just ones that meaningfully change the value of the selector)
e.g.
// good stuff, returning existing reference
const user = useSelector(state => state.users);
// bad! new reference
const user = useSelector(state => state.users.map(user=>user.name));

eslint extends airbnb/hooks
Getting Started with Create React App
This project was bootstrapped with Create React App.
Available Scripts
In the project directory, you can run:
npm start
Runs the app in the development mode.

Open http://localhost:3000 to view it in the browser.
The page will reload if you make edits.

You will also see any lint errors in the console.
npm test
Launches the test runner in the interactive watch mode.

See the section about running tests for more information.
npm run build
Builds the app for production to the build folder.

It correctly bundles React in production mode and optimizes the build for the best performance.
The build is minified and the filenames include the hashes.

Your app is ready to be deployed!
See the section about deployment for more information.
npm run eject
Note: this is a one-way operation. Once you eject, you can’t go back!
If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.
Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.
You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.
Learn More
You can learn more in the Create React App documentation.
To learn React, check out the React documentation.
Code Splitting
This section has moved here: https://facebook.github.io/create-react-app/docs/code-splitting
Analyzing the Bundle Size
This section has moved here: https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size
Making a Progressive Web App
This section has moved here: https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app
Advanced Configuration
This section has moved here: https://facebook.github.io/create-react-app/docs/advanced-configuration
Deployment
This section has moved here: https://facebook.github.io/create-react-app/docs/deployment
npm run build fails to minify
This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify
About
No description, website, or topics provided.
Resources
Readme
Activity
Stars
1 star
Watchers
1 watching
Forks
0 forks
Report repository
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Packages
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
GitHub - kaplantm/hook-optimization · GitHub
Skip to content
BranchesTags
Repository files navigation
Hooks / Optimization Roundtable
Takeaways:
Memoization
Memoization is an optimization technique, used primarily to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again.
useEffect
  • Used to perform side effects / react to changes in variables
  • By default runs every render, unless an array of dependencies is provided
useCallback
  • Returns a memoized callback.
useMemo
  • Returns a memoized value.
  • Only recomputes value when dependencies change.
  • Can be used to stablize unstable inputs, to avoid unncessarily re-computer complex logic
  • Not the place for side effects. Those go in useEffect.
  • By default runs every render, unless an array of dependencies is provided
Hook dependencies
  • Some hooks take an array of dependencies are compared based on reference or value (for primitive types). So it you pass in an object/array/function that does not have a stable reference, useEffect will run a lot. Don't do that!
  • Make sure to add airbnb/hooks to your eslint to see warnings about missing or unstable dependencies
React.memo
  • React.memo is a higher order component
  • Components will rerender when their parents re-render, even it there props don't change. You can avoid this by wrapping your child component in memo(). It iwll only rerener when internal state/hooks/context changes, and when its props change.
Vaguely Related: Redux Selectors
  • useSelector from redux uses similar logic for dependencies So that is also a scenario you want to be careful of returning new objects vs references to existing ones.
  • More info
  • By creating into a new object/reference it will always return a new object. Therefore your component will re-render on every action that gets dispatched (not just ones that meaningfully change the value of the selector)
e.g.
// good stuff, returning existing reference
const user = useSelector(state => state.users);
// bad! new reference
const user = useSelector(state => state.users.map(user=>user.name));

eslint extends airbnb/hooks
Getting Started with Create React App
This project was bootstrapped with Create React App.
Available Scripts
In the project directory, you can run:
npm start
Runs the app in the development mode.

Open http://localhost:3000 to view it in the browser.
The page will reload if you make edits.

You will also see any lint errors in the console.
npm test
Launches the test runner in the interactive watch mode.

See the section about running tests for more information.
npm run build
Builds the app for production to the build folder.

It correctly bundles React in production mode and optimizes the build for the best performance.
The build is minified and the filenames include the hashes.

Your app is ready to be deployed!
See the section about deployment for more information.
npm run eject
Note: this is a one-way operation. Once you eject, you can’t go back!
If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.
Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.
You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.
Learn More
You can learn more in the Create React App documentation.
To learn React, check out the React documentation.
Code Splitting
This section has moved here: https://facebook.github.io/create-react-app/docs/code-splitting
Analyzing the Bundle Size
This section has moved here: https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size
Making a Progressive Web App
This section has moved here: https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app
Advanced Configuration
This section has moved here: https://facebook.github.io/create-react-app/docs/advanced-configuration
Deployment
This section has moved here: https://facebook.github.io/create-react-app/docs/deployment
npm run build fails to minify
This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify
About
No description, website, or topics provided.
Resources
Readme
Activity
Stars
1 star
Watchers
1 watching
Forks
0 forks
Report repository
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Contributors
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