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javascript-koans

Based on Edgecase's fantastic Ruby koans, the goal of the Javascript koans is to teach you Javascript programming through testing.

When you first run the koans, you'll be presented with a runtime error and a stack trace indicating where the error occurred. Your goal is to make the error go away. As you fix each error, you should learn something about the Javascript language and functional programming in general.

Your journey towards Javascript enlightenment starts in the koans/AboutExpects.js file. These koans will be very simple, so don't overthink them! As you progress through more koans, more and more Javascript syntax will be introduced which will allow you to solve more complicated problems and use more advanced techniques.

Running the Koans

Simply navigate to the Javascript Koans folder using a file browser, and double click on KoansRunnner.html.

Any browser will do, but for the best results Firefox or Chrome is recommended. More stack trace information shows up for javascript on these browsers.

The first error will be in koans/AboutExpects.js. Fix the first test and refresh the browser. Rinse and repeat until all tests turn green.

The test runner used is Jasmine with a customized report viewer.

Changelog

  • v3 - Nov 2010 - Moved out of branch of functional-koans project, into own top level project
  • v2 - Sept 2010 - Second version based on jasmine (Thanks Greg Malcolm!)
  • v1 - July 2010 - First version based on jsTestDriver

Acknowledgements

  • Dick Wall (the Java posse) - for bringing the idea of koans to my attention
  • Edgecase - for the great Ruby Koans
  • Douglas Crockford - for Javascript; the good bits

MIT Licensed

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Koans to learn Javascript

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Readme
MIT license
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, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
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(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
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btn.onmouseover = function() { this.style.opacity = '1'; };
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btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
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observer.observe(document.body, { childList: true, subtree: true });
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} 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 - MikeJDeck/javascript-koans: Koans to learn Javascript · GitHub
Skip to content
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Repository files navigation
javascript-koans
Based on Edgecase's fantastic
Ruby koans, the goal of the
Javascript koans is to teach you Javascript programming through
testing.
When you first run the koans, you'll be presented with a runtime error and a
stack trace indicating where the error occurred. Your goal is to make the
error go away. As you fix each error, you should learn something about the
Javascript language and functional programming in general.
Your journey towards Javascript enlightenment starts in the koans/AboutExpects.js file. These
koans will be very simple, so don't overthink them! As you progress through
more koans, more and more Javascript syntax will be introduced which will allow
you to solve more complicated problems and use more advanced techniques.
Running the Koans
Simply navigate to the Javascript Koans folder using a file browser, and
double click on KoansRunnner.html.
Any browser will do, but for the best results Firefox or Chrome is
recommended. More stack trace information shows up for javascript on these
browsers.
The first error will be in koans/AboutExpects.js. Fix the first test and
refresh the browser. Rinse and repeat until all tests turn green.
The test runner used is Jasmine with a customized report viewer.
Changelog
  • v3 - Nov 2010 - Moved out of branch of functional-koans project, into own top level project
  • v2 - Sept 2010 - Second version based on jasmine (Thanks Greg Malcolm!)
  • v1 - July 2010 - First version based on jsTestDriver
Acknowledgements
  • Dick Wall (the Java posse) - for bringing the idea of koans to my attention
  • Edgecase - for the great Ruby Koans
  • Douglas Crockford - for Javascript; the good bits
MIT Licensed
About
Koans to learn Javascript
Resources
Readme
MIT license
Activity
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1 watching
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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 - MikeJDeck/javascript-koans: Koans to learn Javascript · GitHub
Skip to content
BranchesTags
Repository files navigation
javascript-koans
Based on Edgecase's fantastic
Ruby koans, the goal of the
Javascript koans is to teach you Javascript programming through
testing.
When you first run the koans, you'll be presented with a runtime error and a
stack trace indicating where the error occurred. Your goal is to make the
error go away. As you fix each error, you should learn something about the
Javascript language and functional programming in general.
Your journey towards Javascript enlightenment starts in the koans/AboutExpects.js file. These
koans will be very simple, so don't overthink them! As you progress through
more koans, more and more Javascript syntax will be introduced which will allow
you to solve more complicated problems and use more advanced techniques.
Running the Koans
Simply navigate to the Javascript Koans folder using a file browser, and
double click on KoansRunnner.html.
Any browser will do, but for the best results Firefox or Chrome is
recommended. More stack trace information shows up for javascript on these
browsers.
The first error will be in koans/AboutExpects.js. Fix the first test and
refresh the browser. Rinse and repeat until all tests turn green.
The test runner used is Jasmine with a customized report viewer.
Changelog
  • v3 - Nov 2010 - Moved out of branch of functional-koans project, into own top level project
  • v2 - Sept 2010 - Second version based on jasmine (Thanks Greg Malcolm!)
  • v1 - July 2010 - First version based on jsTestDriver
Acknowledgements
  • Dick Wall (the Java posse) - for bringing the idea of koans to my attention
  • Edgecase - for the great Ruby Koans
  • Douglas Crockford - for Javascript; the good bits
MIT Licensed
About
Koans to learn Javascript
Resources
Readme
MIT license
Activity
Stars
0 stars
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) {
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terms.forEach(function(term) {
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var frag = document.createDocumentFragment();
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parts.forEach(function(part, i) {
if (i % 2 === 0) {
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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 - MikeJDeck/javascript-koans: Koans to learn Javascript · GitHub
Skip to content
BranchesTags
Repository files navigation
javascript-koans
Based on Edgecase's fantastic
Ruby koans, the goal of the
Javascript koans is to teach you Javascript programming through
testing.
When you first run the koans, you'll be presented with a runtime error and a
stack trace indicating where the error occurred. Your goal is to make the
error go away. As you fix each error, you should learn something about the
Javascript language and functional programming in general.
Your journey towards Javascript enlightenment starts in the koans/AboutExpects.js file. These
koans will be very simple, so don't overthink them! As you progress through
more koans, more and more Javascript syntax will be introduced which will allow
you to solve more complicated problems and use more advanced techniques.
Running the Koans
Simply navigate to the Javascript Koans folder using a file browser, and
double click on KoansRunnner.html.
Any browser will do, but for the best results Firefox or Chrome is
recommended. More stack trace information shows up for javascript on these
browsers.
The first error will be in koans/AboutExpects.js. Fix the first test and
refresh the browser. Rinse and repeat until all tests turn green.
The test runner used is Jasmine with a customized report viewer.
Changelog
  • v3 - Nov 2010 - Moved out of branch of functional-koans project, into own top level project
  • v2 - Sept 2010 - Second version based on jasmine (Thanks Greg Malcolm!)
  • v1 - July 2010 - First version based on jsTestDriver
Acknowledgements
  • Dick Wall (the Java posse) - for bringing the idea of koans to my attention
  • Edgecase - for the great Ruby Koans
  • Douglas Crockford - for Javascript; the good bits
MIT Licensed
About
Koans to learn Javascript
Resources
Readme
MIT license
Activity
Stars
0 stars
Watchers
1 watching
Forks
0 forks
Report repository
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Packages
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, '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 - MikeJDeck/javascript-koans: Koans to learn Javascript · GitHub
Skip to content
BranchesTags
Repository files navigation
javascript-koans
Based on Edgecase's fantastic
Ruby koans, the goal of the
Javascript koans is to teach you Javascript programming through
testing.
When you first run the koans, you'll be presented with a runtime error and a
stack trace indicating where the error occurred. Your goal is to make the
error go away. As you fix each error, you should learn something about the
Javascript language and functional programming in general.
Your journey towards Javascript enlightenment starts in the koans/AboutExpects.js file. These
koans will be very simple, so don't overthink them! As you progress through
more koans, more and more Javascript syntax will be introduced which will allow
you to solve more complicated problems and use more advanced techniques.
Running the Koans
Simply navigate to the Javascript Koans folder using a file browser, and
double click on KoansRunnner.html.
Any browser will do, but for the best results Firefox or Chrome is
recommended. More stack trace information shows up for javascript on these
browsers.
The first error will be in koans/AboutExpects.js. Fix the first test and
refresh the browser. Rinse and repeat until all tests turn green.
The test runner used is Jasmine with a customized report viewer.
Changelog
  • v3 - Nov 2010 - Moved out of branch of functional-koans project, into own top level project
  • v2 - Sept 2010 - Second version based on jasmine (Thanks Greg Malcolm!)
  • v1 - July 2010 - First version based on jsTestDriver
Acknowledgements
  • Dick Wall (the Java posse) - for bringing the idea of koans to my attention
  • Edgecase - for the great Ruby Koans
  • Douglas Crockford - for Javascript; the good bits
MIT Licensed
About
Koans to learn Javascript
Resources
Readme
MIT license
Activity
Stars
0 stars
Watchers
1 watching
Forks
0 forks
Report repository
Releases
Packages
Contributors
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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 - MikeJDeck/javascript-koans: Koans to learn Javascript · GitHub
Skip to content
BranchesTags
Repository files navigation
javascript-koans
Based on Edgecase's fantastic
Ruby koans, the goal of the
Javascript koans is to teach you Javascript programming through
testing.
When you first run the koans, you'll be presented with a runtime error and a
stack trace indicating where the error occurred. Your goal is to make the
error go away. As you fix each error, you should learn something about the
Javascript language and functional programming in general.
Your journey towards Javascript enlightenment starts in the koans/AboutExpects.js file. These
koans will be very simple, so don't overthink them! As you progress through
more koans, more and more Javascript syntax will be introduced which will allow
you to solve more complicated problems and use more advanced techniques.
Running the Koans
Simply navigate to the Javascript Koans folder using a file browser, and
double click on KoansRunnner.html.
Any browser will do, but for the best results Firefox or Chrome is
recommended. More stack trace information shows up for javascript on these
browsers.
The first error will be in koans/AboutExpects.js. Fix the first test and
refresh the browser. Rinse and repeat until all tests turn green.
The test runner used is Jasmine with a customized report viewer.
Changelog
  • v3 - Nov 2010 - Moved out of branch of functional-koans project, into own top level project
  • v2 - Sept 2010 - Second version based on jasmine (Thanks Greg Malcolm!)
  • v1 - July 2010 - First version based on jsTestDriver
Acknowledgements
  • Dick Wall (the Java posse) - for bringing the idea of koans to my attention
  • Edgecase - for the great Ruby Koans
  • Douglas Crockford - for Javascript; the good bits
MIT Licensed
About
Koans to learn Javascript
Resources
Readme
MIT license
Activity
Stars
0 stars
Watchers
1 watching
Forks
0 forks
Report repository
Releases
Packages
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') {
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observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
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} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
GitHub - MikeJDeck/javascript-koans: Koans to learn Javascript · GitHub
Skip to content
BranchesTags
Repository files navigation
javascript-koans
Based on Edgecase's fantastic
Ruby koans, the goal of the
Javascript koans is to teach you Javascript programming through
testing.
When you first run the koans, you'll be presented with a runtime error and a
stack trace indicating where the error occurred. Your goal is to make the
error go away. As you fix each error, you should learn something about the
Javascript language and functional programming in general.
Your journey towards Javascript enlightenment starts in the koans/AboutExpects.js file. These
koans will be very simple, so don't overthink them! As you progress through
more koans, more and more Javascript syntax will be introduced which will allow
you to solve more complicated problems and use more advanced techniques.
Running the Koans
Simply navigate to the Javascript Koans folder using a file browser, and
double click on KoansRunnner.html.
Any browser will do, but for the best results Firefox or Chrome is
recommended. More stack trace information shows up for javascript on these
browsers.
The first error will be in koans/AboutExpects.js. Fix the first test and
refresh the browser. Rinse and repeat until all tests turn green.
The test runner used is Jasmine with a customized report viewer.
Changelog
  • v3 - Nov 2010 - Moved out of branch of functional-koans project, into own top level project
  • v2 - Sept 2010 - Second version based on jasmine (Thanks Greg Malcolm!)
  • v1 - July 2010 - First version based on jsTestDriver
Acknowledgements
  • Dick Wall (the Java posse) - for bringing the idea of koans to my attention
  • Edgecase - for the great Ruby Koans
  • Douglas Crockford - for Javascript; the good bits
MIT Licensed
About
Koans to learn Javascript
Resources
Readme
MIT license
Activity
Stars
0 stars
Watchers
1 watching
Forks
0 forks
Report repository
Releases
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 - MikeJDeck/javascript-koans: Koans to learn Javascript · GitHub
Skip to content
BranchesTags
Repository files navigation
javascript-koans
Based on Edgecase's fantastic
Ruby koans, the goal of the
Javascript koans is to teach you Javascript programming through
testing.
When you first run the koans, you'll be presented with a runtime error and a
stack trace indicating where the error occurred. Your goal is to make the
error go away. As you fix each error, you should learn something about the
Javascript language and functional programming in general.
Your journey towards Javascript enlightenment starts in the koans/AboutExpects.js file. These
koans will be very simple, so don't overthink them! As you progress through
more koans, more and more Javascript syntax will be introduced which will allow
you to solve more complicated problems and use more advanced techniques.
Running the Koans
Simply navigate to the Javascript Koans folder using a file browser, and
double click on KoansRunnner.html.
Any browser will do, but for the best results Firefox or Chrome is
recommended. More stack trace information shows up for javascript on these
browsers.
The first error will be in koans/AboutExpects.js. Fix the first test and
refresh the browser. Rinse and repeat until all tests turn green.
The test runner used is Jasmine with a customized report viewer.
Changelog
  • v3 - Nov 2010 - Moved out of branch of functional-koans project, into own top level project
  • v2 - Sept 2010 - Second version based on jasmine (Thanks Greg Malcolm!)
  • v1 - July 2010 - First version based on jsTestDriver
Acknowledgements
  • Dick Wall (the Java posse) - for bringing the idea of koans to my attention
  • Edgecase - for the great Ruby Koans
  • Douglas Crockford - for Javascript; the good bits
MIT Licensed
About
Koans to learn Javascript
Resources
Readme
MIT license
Activity
Stars
0 stars
Watchers
1 watching
Forks
0 forks
Report repository
Releases
Packages
Contributors
Languages