Manifest - content scripts

The "content_scripts" key specifies a statically loaded JavaScript or CSS file to be used every time a page is opened that matches a certain URL pattern. Extensions can also inject content scripts programmatically, see Injecting Scripts for details.

Manifest

These are the supported keys for "content_scripts". Only the "matches" key and either "js" or "css" are required.

manifest.json

{
 "name": "My extension",
 ...
 "content_scripts": [
   {
     "matches": ["https://*.example.com/*"],
     "css": ["my-styles.css"],
     "js": ["content-script.js"],
     "exclude_matches": ["*://*/*foo*"],
     "include_globs": ["*example.com/???s/*"],
     "exclude_globs": ["*bar*"],     
     "all_frames": false,
     "match_origin_as_fallback": false,
     "match_about_blank": false,
     "run_at": "document_idle",
     "world": "ISOLATED",
   }
 ],
 ...
}

Files

Each file must contain a relative path to a resource in the extension's root directory. Leading slashes (/) are automatically trimmed. The "run_at" key specifies when each file will be injected.

"css" - Array

Optional. An array of CSS file paths, injected in the order of this array, and before any DOM construction or page rendering occurs.

"js" - Array,

Optional. An array of JavaScript file paths, injected in the order they appear in this array, after css files are injected. Each string in the array must be a relative path to a resource in the extension's root directory. Leading slashes ('/') are automatically trimmed.

Match URLs

Only the "matches" property is required. Then you can use "exclude_matches", "include_globs", and "exclude_globs" to customize which URLs to inject code into. The "matches" key will trigger a warning.

"matches" - Array

Required. Specifies which URL patterns to inject the content scripts into. See Match Patterns for syntax.

"exclude_matches" - Array

Optional. Excludes the URL patterns to inject the content scripts into. See Match Patterns for syntax.

"include_globs" - Array

Optional. Applied after matches to include only those URLs that also match this glob. Intended to emulate the @include Greasemonkey keyword.

"exclude_globs" - Array

Optional. Applied after matches to exclude URLs that match this glob. Intended to emulate the @exclude Greasemonkey keyword.

Glob URLs are those that contain "wildcards" * and question marks. The wildcard * matches any string of any length, including an empty string, while the question mark ? matches any single character.

The content script is injected into a page if:

• Its URL matches any "matches" and "include_globs" patterns.
• And the URL doesn't match "exclude_matches" or "exclude_globs" patterns.

Globs and URL matching examples

"include_globs"

manifest.json

{
  ...
  "content_scripts": [
    {
      "matches": ["https://*.example.com/*"],
      "include_globs": ["https://???.example.com/foo/*"],
      "js": ["content-script.js"]
    }
  ],
  ...
}

Matches

https://www.example.com/foo/bar
https://the.example.com/foo/

Does not match

https://my.example.com/foo/bar
https://example.com/foo/*
https://www.example.com/foo

manifest.json

{
  ...
  "content_scripts": [
    {
      "matches": ["https://*.example.com/*"],
      "include_globs": ["*example.com/???s/*"],
      "js": ["content-script.js"]
    }
  ],
  ...
}

Matches

https://www.example.com/arts/index.html
https://www.example.com/jobs/index.html

Does not match

https://www.example.com/sports/index.html
https://www.example.com/music/index.html

"exclude_globs"

manifest.json

{
  ...
  "content_scripts": [
    {
      "matches": ["https://*.example.com/*"],
      "exclude_globs": ["*science*"],
      "js": ["content-script.js"]
    }
  ],
  ...
}

Matches

https://history.example.com
https://.example.com/music

Does not match

https://science.example.com
https://www.example.com/science

Advanced customization example

manifest.json

{
  ...
  "content_scripts": [
    {
      "matches": ["https://*.example.com/*"],
      "exclude_matches": ["*://*/*business*"],
      "include_globs": ["*example.com/???s/*"],
      "exclude_globs": ["*science*"],
      "js": ["content-script.js"]
    }
  ],
  ...
}

Matches

https://www.example.com/arts/index.html
https://.example.com/jobs/index.html

Does not match

https://science.example.com
https://www.example.com/jobs/business
https://www.example.com/science

Frames

The "all_frames" key specifies if the content script should be injected into all frames matching the specified URL requirements. If set to false it will only inject into the topmost frame. It can be used along with "match_about_blank" to inject into an about:blank frame.

To inject into other frames like data:, blob:, and filesystem:, set the "match_origin_as_fallback" to true. For details, see Inject in related frames

"all_frames" Boolean

Optional. Defaults to false, meaning that only the top frame is matched. If set to true, it will inject into all frames, even if the frame is not the topmost frame in the tab. Each frame is checked independently for URL requirements, it won't inject into child frames if the URL requirements are not met.

"match_about_blank"- Boolean

Optional. Defaults to false. Whether the script should inject into an about:blank frame where the parent URL matches one of the patterns declared in "matches".

"match_origin_as_fallback" - Boolean

Optional. Defaults to false. Whether the script should inject in frames that were created by a matching origin, but whose URL or origin may not directly match the pattern. These include frames with different schemes, such as about:, data:, blob:, and filesystem:.

Run time and execution environment

By default, content scripts are injected when the document and all resources are finished loading, and live in a private isolated execution environment that isn't accessible to the page or other extensions. You can change these defaults in the following keys:

"run_at" - document_start | document_end | document_idle

Optional. Specifies when the script should be injected into the page. It corresponds with the loading states of Document.readyState:

• "document_start": the DOM is still loading.
• "document_end": the page's resources are still loading
• "document_idle": the DOM and resources have finished loading. This is the default.

"world" - ISOLATED | MAIN

Optional. The JavaScript world for a script to execute within. Defaults to "ISOLATED", which is the execution environment unique to the content script. Choosing the "MAIN" world means the script will share the execution environment with the host page's JavaScript. See Work in isolated worlds to learn more.

Warning: There are risks involved when using the "MAIN" world. The host page can access and interfere with the injected script. See Work in isolated worlds to learn more.

Example

See the Run on every page tutorial to build an extension that injects a content script in the manifest.