Chrome扩展：如何绕过限制向新标签页注入CSS/JS？

Alright, let's break down how to inject CSS/JS into Chrome's default new tab page, since we know content scripts don't work on chrome:// URLs and chrome_url_overrides fully replaces the tab. Here are the most practical solutions:

Option 1: Use the DevTools Protocol via the chrome.debugger API #

This is the go-to method if you want to modify the actual default new tab without replacing it entirely. The DevTools Protocol lets you bypass Chrome's restrictions on chrome:// URLs by acting like Chrome's own DevTools.

Step-by-step setup: #

1. Update your manifest.json to include the required permissions:

   {
     "manifest_version": 3,
     "name": "New Tab Customizer",
     "version": "1.0",
     "permissions": ["debugger", "tabs"]
   }
   

2. Add a background script to detect new tabs and inject your code:

   chrome.tabs.onCreated.addListener(async (tab) => {
     // Only target the default new tab
     if (tab.url === 'chrome://newtab/') {
       try {
         // Attach the debugger to the tab
         await chrome.debugger.attach({ tabId: tab.id }, '1.3');
         
         // Inject your custom JavaScript
         await chrome.debugger.sendCommand({ tabId: tab.id }, 'Runtime.evaluate', {
           expression: `
             // Example: Modify the search bar placeholder
             document.querySelector('input[aria-label="Search"]').placeholder = "Custom Search...";
           `
         });
         
         // Inject your custom CSS
         await chrome.debugger.sendCommand({ tabId: tab.id }, 'CSS.addStyleSheet', {
           styleSheet: `
             // Example: Change the background color
             body { background: #eef2f5 !important; }
             .shortcut-wrapper { border-radius: 12px !important; }
           `
         });
         
         // Detach the debugger once done (cleanup)
         chrome.debugger.detach({ tabId: tab.id });
       } catch (err) {
         console.log('Debugger error:', err);
       }
     }
   });
   

3. Note for users: The first time they use your extension, Chrome will show a prompt asking to allow debugging. This is a security measure, but it's only a one-time prompt (unless they reset extension permissions).

Option 2: Replace the new tab with a custom wrapper page #

If the debugger prompt isn't ideal for your use case, you can use chrome_url_overrides to replace the new tab with your own page that mimics the default new tab's functionality, then add your custom CSS/JS directly to it.

Step-by-step setup: #

1. Update your manifest.json to override the new tab:

   {
     "manifest_version": 3,
     "name": "Custom New Tab",
     "version": "1.0",
     "chrome_url_overrides": {
       "newtab": "newtab.html"
     },
     "permissions": ["topSites", "bookmarks"]
   }
   

2. Create your newtab.html with custom content. You can use Chrome's APIs to replicate the default shortcuts and search bar:

   <!DOCTYPE html>
   <html>
   <head>
     <title>Custom New Tab</title>
     <style>
       /* Your custom CSS here */
       body { margin: 0; padding: 2rem; font-family: Arial, sans-serif; background: #f8f9fa; }
       .search-bar { width: 500px; margin: 2rem auto; padding: 0.8rem; border-radius: 24px; border: 1px solid #ddd; }
       .shortcuts { display: grid; grid-template-columns: repeat(8, 1fr); gap: 1.5rem; max-width: 800px; margin: 3rem auto; }
       .shortcut { text-align: center; padding: 1rem; border-radius: 8px; background: white; }
     </style>
   </head>
   <body>
     <input type="text" class="search-bar" placeholder="Search or enter URL...">
     <div class="shortcuts" id="shortcuts"></div>
   
     <script>
       // Your custom JavaScript here
       // Fetch top sites to replicate default shortcuts
       chrome.topSites.get((sites) => {
         const shortcutsContainer = document.getElementById('shortcuts');
         sites.forEach(site => {
           const shortcut = document.createElement('div');
           shortcut.className = 'shortcut';
           shortcut.innerHTML = `<img src="https://www.google.com/s2/favicons?domain=${site.url}" width="32"><br>${site.title}`;
           shortcut.addEventListener('click', () => window.location.href = site.url);
           shortcutsContainer.appendChild(shortcut);
         });
       });
   
       // Add search functionality
       document.querySelector('.search-bar').addEventListener('keypress', (e) => {
         if (e.key === 'Enter') {
           const query = e.target.value;
           window.location.href = `https://www.google.com/search?q=${encodeURIComponent(query)}`;
         }
       });
     </script>
   </body>
   </html>
   

This method gives you full control over the new tab, and you can customize every part of it without any permission prompts.

Which one should you choose? #

• Use Option 1 if you need to modify the existing default new tab (e.g., tweak styles or add small scripts without changing the overall layout).
• Use Option 2 if you want a fully custom new tab experience that matches the default's core features but with your own twists.

内容的提问来源于stack exchange，提问作者Ryan Jiang