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Fix the snake!

In this task, you'll fix a problem with this simple web-based game:

Broken Snake Game

The way the game is supposed to work is that the snake moves up, down, left, and right (using the keyboard). Every time the snake eats a dot, it grows in length by one. If the snake collides with itself, the game is over.

As you'll see when you play the game, the snake does not move up, down, left, and right. It just seems to move diagonally, and when you press the arrow keys in certain directions, the game ends.

To find and fix this defect, you'll use this debugging strategy:

Open the debugging strategy in a new tab

Follow the strategy using the strategy execution tool to find and fix the following failure. You have up to 15 minutes. When you believe you've found the best fix, tell the experimenter which text on which line of code you changed (e.g., line 27, replace "hello" with "goodbye").

, '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" + '

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Fix the snake!
In this task, you'll fix a problem with this simple web-based game:
Broken Snake Game
The way the game is supposed to work is that the snake moves up, down, left, and right (using the keyboard). Every time the snake eats a dot, it grows in length by one. If the snake collides with itself, the game is over.
As you'll see when you play the game, the snake does not move up, down, left, and right. It just seems to move diagonally, and when you press the arrow keys in certain directions, the game ends.
To find and fix this defect, you'll use this debugging strategy:
Open the debugging strategy in a new tab
Follow the strategy using the strategy execution tool to find and fix the following failure. You have up to 15 minutes. When you believe you've found the best fix, tell the experimenter which text on which line of code you changed (e.g., line 27, replace "hello" with "goodbye").

, '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('^' + ".*" + '

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Fix the snake!
In this task, you'll fix a problem with this simple web-based game:
Broken Snake Game
The way the game is supposed to work is that the snake moves up, down, left, and right (using the keyboard). Every time the snake eats a dot, it grows in length by one. If the snake collides with itself, the game is over.
As you'll see when you play the game, the snake does not move up, down, left, and right. It just seems to move diagonally, and when you press the arrow keys in certain directions, the game ends.
To find and fix this defect, you'll use this debugging strategy:
Open the debugging strategy in a new tab
Follow the strategy using the strategy execution tool to find and fix the following failure. You have up to 15 minutes. When you believe you've found the best fix, tell the experimenter which text on which line of code you changed (e.g., line 27, replace "hello" with "goodbye").

, '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('^' + ".*" + '

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Fix the snake!
In this task, you'll fix a problem with this simple web-based game:
Broken Snake Game
The way the game is supposed to work is that the snake moves up, down, left, and right (using the keyboard). Every time the snake eats a dot, it grows in length by one. If the snake collides with itself, the game is over.
As you'll see when you play the game, the snake does not move up, down, left, and right. It just seems to move diagonally, and when you press the arrow keys in certain directions, the game ends.
To find and fix this defect, you'll use this debugging strategy:
Open the debugging strategy in a new tab
Follow the strategy using the strategy execution tool to find and fix the following failure. You have up to 15 minutes. When you believe you've found the best fix, tell the experimenter which text on which line of code you changed (e.g., line 27, replace "hello" with "goodbye").

, '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" + '

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Fix the snake!
In this task, you'll fix a problem with this simple web-based game:
Broken Snake Game
The way the game is supposed to work is that the snake moves up, down, left, and right (using the keyboard). Every time the snake eats a dot, it grows in length by one. If the snake collides with itself, the game is over.
As you'll see when you play the game, the snake does not move up, down, left, and right. It just seems to move diagonally, and when you press the arrow keys in certain directions, the game ends.
To find and fix this defect, you'll use this debugging strategy:
Open the debugging strategy in a new tab
Follow the strategy using the strategy execution tool to find and fix the following failure. You have up to 15 minutes. When you believe you've found the best fix, tell the experimenter which text on which line of code you changed (e.g., line 27, replace "hello" with "goodbye").

, '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('^' + ".*" + '

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debugging-1-guided.md
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15 lines (8 loc) · 973 Bytes
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Fix the snake!
In this task, you'll fix a problem with this simple web-based game:
Broken Snake Game
The way the game is supposed to work is that the snake moves up, down, left, and right (using the keyboard). Every time the snake eats a dot, it grows in length by one. If the snake collides with itself, the game is over.
As you'll see when you play the game, the snake does not move up, down, left, and right. It just seems to move diagonally, and when you press the arrow keys in certain directions, the game ends.
To find and fix this defect, you'll use this debugging strategy:
Open the debugging strategy in a new tab
Follow the strategy using the strategy execution tool to find and fix the following failure. You have up to 15 minutes. When you believe you've found the best fix, tell the experimenter which text on which line of code you changed (e.g., line 27, replace "hello" with "goodbye").

, '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('^' + ".*" + '

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debugging-1-guided.md
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15 lines (8 loc) · 973 Bytes
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Fix the snake!
In this task, you'll fix a problem with this simple web-based game:
Broken Snake Game
The way the game is supposed to work is that the snake moves up, down, left, and right (using the keyboard). Every time the snake eats a dot, it grows in length by one. If the snake collides with itself, the game is over.
As you'll see when you play the game, the snake does not move up, down, left, and right. It just seems to move diagonally, and when you press the arrow keys in certain directions, the game ends.
To find and fix this defect, you'll use this debugging strategy:
Open the debugging strategy in a new tab
Follow the strategy using the strategy execution tool to find and fix the following failure. You have up to 15 minutes. When you believe you've found the best fix, tell the experimenter which text on which line of code you changed (e.g., line 27, replace "hello" with "goodbye").

, '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); }
})();
})();

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Fix the snake!
In this task, you'll fix a problem with this simple web-based game:
Broken Snake Game
The way the game is supposed to work is that the snake moves up, down, left, and right (using the keyboard). Every time the snake eats a dot, it grows in length by one. If the snake collides with itself, the game is over.
As you'll see when you play the game, the snake does not move up, down, left, and right. It just seems to move diagonally, and when you press the arrow keys in certain directions, the game ends.
To find and fix this defect, you'll use this debugging strategy:
Open the debugging strategy in a new tab
Follow the strategy using the strategy execution tool to find and fix the following failure. You have up to 15 minutes. When you believe you've found the best fix, tell the experimenter which text on which line of code you changed (e.g., line 27, replace "hello" with "goodbye").