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 one object).

The extension must have the appropriate host permissions for the patterns in contentScriptOptions, or the API call is rejected.

Syntax

let registering = browser.contentScripts.register(
  contentScriptOptions       // object
)

Parameters

• 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 {{Glossary("camel_case", "camel case")}}, rather than underscores ({{Glossary("snake_case", "snake case")}}) — 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 these properties:

    • allFrames {{optional_inline}}
      • : Same as all_frames in the content_scripts key.
    • cookieStoreId {{optional_inline}}
      • : 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 the extension is enabled in private browsing), the tabs of a contextual identity, or a combination of these. See Work with contextual identities for more information.
    • css {{optional_inline}}
      • : 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.
    • cssOrigin {{optional_inline}}
      • : string. The style origin for the injection, either "user", to add the CSS as a user stylesheet, or "author", to add it as an author stylesheet. Defaults to "author". This property is case insensitive.
    • excludeGlobs {{optional_inline}}
      • : Same as exclude_globs in the content_scripts key.
    • excludeMatches {{optional_inline}}
      • : Same as exclude_matches in the content_scripts key.
    • includeGlobs {{optional_inline}}
      • : Same as include_globs in the content_scripts key.
    • js {{optional_inline}}
      • : 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.
    • matchAboutBlank {{optional_inline}}
      • : Same as match_about_blank in the content_scripts key.
    • matchOriginAsFallback {{optional_inline}}
      • : Same as match_origin_as_fallback in the content_scripts key.
    • matches
      • : Same as matches in the content_scripts key.
    • runAt {{optional_inline}}
      • : Same as run_at in the content_scripts key.
    • world {{optional_inline}}
      • : The execution environment for a script to execute in. Same as world in the content_scripts key.

Return value

A Promise that will be fulfilled with a {{WebExtAPIRef("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.

Examples

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",
});

{{WebExtExamples}}

Browser compatibility

{{Compat}}