Creating Bookmarklets

Bookmarklet Creation

Critical Requirements

Comment Style - ABSOLUTE

Use ONLY /* */ comments. NEVER use // comments.

Bookmark execution contexts fail with // style. Every comment must use block format.

/* ✓ Correct */
const x = 5; /* inline */

/* ✗ Wrong - breaks bookmarklets */
// const x = 5;
const y = 10; // inline

IIFE Wrapper

All bookmarklets must wrap in IIFE:

(function() {
  /* bookmarklet code */
})();

Protocol Prefix

All delivered bookmarklets must begin with javascript: protocol:

javascript:(function() {
  /* bookmarklet code */
})();

This makes the code immediately usable without requiring manual modification during installation.

Workflow

1. Generate Pretty-Printed Code

Create readable source with:

• 2-space indentation
• Descriptive variable names
• Block comments for key sections
• Logical organization
• Prepend javascript: protocol to the code

This version with javascript: prefix gets stored in GitHub and shown to users, making it ready for installation without manual modification.

2. Provide Installation

Default approach - reference installer:

Install: https://austegard.com/web-utilities/bookmarklet-installer.html

Installer handles:

• Minification with Terser
• URL encoding
• Draggable link generation
• GitHub repo integration

Alternative - generate link programmatically:

Use Terser.js to create installable link if requested:

async function createBookmarkletLink(code, title) {
  const minified = await Terser.minify(code);
  const encoded = encodeURIComponent(minified.code).replace(/'/g, "%27");
  return `<a href="javascript:${encoded}">${title}</a>`;
}

Requires: <script src="https://cdn.jsdelivr.net/npm/terser/dist/bundle.min.js"></script>

3. Deliverables

Always provide:

• Pretty-printed source code with javascript: protocol prepended
• Installation method (installer link or generated link)
• Brief description of functionality
• Usage instructions

The code should be delivered in a format ready for direct use - users should be able to copy the entire code block (including javascript:) without modification.

Code Standards

Error Handling

(function() {
  try {
    /* main logic */
  } catch (error) {
    console.error('Bookmarklet error:', error);
    alert('Operation failed: ' + error.message);
  }
})();

Console Logging

Include debug traces by default:

console.log('Bookmarklet: Starting');
/* operations */
console.log('Bookmarklet: Complete');

User Feedback

/* Success */
alert('✓ Content copied to clipboard');

/* Error */
alert('✗ Failed to access clipboard');

Common Patterns

DOM Manipulation

(function() {
  const element = document.querySelector('.target');
  if (!element) {
    alert('Element not found');
    return;
  }
  /* manipulate element */
})();

Data Extraction

(function() {
  const data = Array.from(document.querySelectorAll('.item'))
    .map(item => ({
      title: item.querySelector('.title')?.textContent.trim(),
      value: item.querySelector('.value')?.textContent.trim()
    }));
  
  console.log('Extracted:', data);
})();

Clipboard Operations

(function() {
  const text = 'content to copy';
  navigator.clipboard.writeText(text)
    .then(() => alert('✓ Copied'))
    .catch(err => {
      console.error('Clipboard error:', err);
      alert('✗ Copy failed');
    });
})();

Dynamic Library Loading

(function() {
  if (typeof someLibrary === 'undefined') {
    const script = document.createElement('script');
    script.src = 'https://cdn.example.com/library.js';
    script.onload = function() {
      /* proceed with logic */
    };
    document.head.appendChild(script);
  }
})();

Browser Compatibility

Provide fallbacks for unsupported features:

if (!navigator.clipboard) {
  alert('Clipboard API not supported');
  return;
}

Constraints

Cannot use:

• External files (CSS, images) without embedding
• Build tools or preprocessing
• // style comments

Can use:

• Fetch API
• localStorage/sessionStorage
• Modern browser APIs
• CDN libraries (loaded dynamically)

Testing

Before delivering:

• Verify no // comments exist
• Test in browser console wrapped in IIFE
• Check error handling with missing DOM elements
• Verify user feedback for all paths

Example Output

javascript:(function() {
  /* Pretty-printed bookmarklet code */
})();

Install: https://austegard.com/web-utilities/bookmarklet-installer.html

Extracts all links from current page and copies to clipboard as markdown list. Works on any webpage.

GitHub Storage

User repository: https://github.com/oaustegard/bookmarklets

Pretty-printed format matches storage requirements. Installer loads directly from this repo.