contentScripts.register()

Use this function to register one or more content scripts.

It accepts one parameter, which is an object with similar properties to the objects given in the content_scripts manifest key (but note that content_scripts is an array of objects, while the argument to register() is a single object).

This is an asynchronous function that returns a Promise.

contentScriptOptions

object. A RegisteredContentScriptOptions object representing the content scripts to register. It has similar syntax to the objects in the content_scripts manifest key array. The differences are:

• property names use camelCase, rather than underscores (for example, excludeMatches, not exclude_matches
• the js and css properties allow you to register strings as well as URLs, so their syntax has to distinguish these types.

The RegisteredContentScriptOptions object has the following properties:

allFramesOptional

Same as all_frames in the content_scripts key.

cookieStoreId Optional

A string or array of strings. Registers the content script in the tabs that belong to one or more cookie store IDs. This enables scripts to be registered for all default or non-contextual identity tabs, private browsing tabs (if extensions are enabled in private browsing), the tabs of a contextual identity, or a combination of these.

cssOptional

An array of objects. Each object has either a property named file, which is a URL starting at the extension's manifest.json and pointing to a CSS file to register, or a property named code, which is some CSS code to register.

excludeGlobsOptional

Same as exclude_globs in the content_scripts key.

excludeMatchesOptional

Same as exclude_matches in the content_scripts key.

includeGlobsOptional

Same as include_globs in the content_scripts key.

jsOptional

An array of objects. Each object has either a property named file, which is a URL starting at the extension's manifest.json and pointing to a JavaScript file to register, or a property named code, which is some JavaScript code to register.

matchAboutBlankOptional

Same as match_about_blank in the content_scripts key.

matches

Same as matches in the content_scripts key.

runAtOptional

Same as run_at in the content_scripts key.

A Promise that will be fulfilled with a contentScripts.RegisteredContentScript object that you can use to unregister the content scripts.

Currently, content scripts are unregistered when the related extension page (from which the content scripts were registered) is unloaded, so you should register a content script from an extension page that persists at least as long as you want the content scripts to stay registered.

This example registers the defaultCode content script for all .org URLs:

const defaultHosts = "*://*.org/*";
const defaultCode = "document.body.innerHTML = '<h1>This page has been eaten<h1>'";

async function register(hosts, code) {

  return await browser.contentScripts.register({
    matches: [hosts],
    js: [{code}],
    runAt: "document_idle"
  });

}

let registered = register(defaultHosts, defaultCode);

This code registers the JS file at content_scripts/example.js:

const scriptObj = await browser.contentScripts.register({
  "js": [{file: "/content_scripts/example.js"}],
  "matches": ["<all_urls>"],
  "allFrames": true,
  "runAt": "document_start"
});

• content-script-register