tabs.executeScript()

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Injects JavaScript code into a page.

[!NOTE] When using Manifest V3 or higher, use {{WebExtAPIRef("scripting.executeScript()")}}  to execute scripts.

You can inject code into pages whose URL can be expressed using a match pattern. To do so, its scheme must be one of: http, https, or file.

You must have the permission for the page’s URL—either explicitly, as a host permission—or, via the activeTab permission. Note that some special pages do not allow this permission, including reader view, view-source, and PDF viewer pages.

You can also inject code into pages packaged with your own extension:

browser.tabs.create({ url: "/my-page.html" }).then(() => {
  browser.tabs.executeScript({
    code: `console.log('location:', window.location.href);`,
  });
});

You don’t need any special permissions to do this.

You cannot inject code into any of the browser’s built-in pages, such as: about:debugging, about:addons, or the page that opens when you open a new empty tab.

The scripts you inject are called content scripts.

This is an asynchronous function that returns a Promise.

Syntax

let executing = browser.tabs.executeScript(
  tabId,                 // optional integer
  details                // object
)

Parameters

• tabId {{optional_inline}} 

  • : integer. The ID of the tab in which to run the script.

    Defaults to the active tab of the current window.

• details

  • : An object describing the script to run.

    It contains the following properties:

    • allFrames {{optional_inline}} 

      • : boolean. If true, the code will be injected into all frames of the current page.

        If true and frameId is set, then it will raise an error. (frameId and allFrames are mutually exclusive.)

        If it is false, code is only injected into the top frame.

        Defaults to false.

    • code {{optional_inline}} 

      • : string. Code to inject, as a text string.

        [!WARNING] Don’t use this property to interpolate untrusted data into JavaScript, as this could lead to a security issue.

    • file {{optional_inline}} 

      • : string. Path to a file containing the code to inject.

        • In Firefox, relative URLs not starting at the extension root are resolved relative to the current page URL.
        • In Chrome, these URLs are resolved relative to the extension’s base URL.

        To work cross-browser, you can specify the path as a relative URL, starting at the extension’s root, like this: "/path/to/script.js".

    • frameId {{optional_inline}} 

      • : integer. The frame where the code should be injected.

        Defaults to 0 (the top-level frame).

    • matchAboutBlank {{optional_inline}} 

      • : boolean. If true, the code will be injected into embedded about:blank and about:srcdoc frames if your extension has access to their parent document. The code cannot be inserted in top-level about: frames.

        Defaults to false.

    • runAt {{optional_inline}} 

      • : {{WebExtAPIRef('extensionTypes.RunAt')}} . The soonest that the code will be injected into the tab.

        Defaults to "document_idle".

Return value

A Promise that will resolve to an array of objects. The array’s values represent the result of the script in every injected frame.

The result of the script is the last evaluated statement, which is similar to what would be output (the results, not any console.log() output) if you executed the script in the Web Console. For example, consider a script like this:

let foo = "my result";
foo;

Here the results array will contain the string “my result” as an element.

The result values must be structured cloneable (see Data cloning algorithm).

[!NOTE] The last statement may be also a Promise, but this feature is unsupported by webextension-polyfill library.

If any error occurs, the promise will be rejected with an error message.

Examples

This example executes a one-line code snippet in the currently active tab:

function onExecuted(result) {
  console.log(`We made it green`);
}

function onError(error) {
  console.log(`Error: ${error}`);
}

const makeItGreen = 'document.body.style.border = "5px solid green"';

const executing = browser.tabs.executeScript({
  code: makeItGreen,
});
executing.then(onExecuted, onError);

This example executes a script from a file (packaged with the extension) called "content-script.js". The script is executed in the currently active tab. The script is executed in subframes as well as the main document:

function onExecuted(result) {
  console.log(`We executed in all subframes`);
}

function onError(error) {
  console.log(`Error: ${error}`);
}

const executing = browser.tabs.executeScript({
  file: "/content-script.js",
  allFrames: true,
});
executing.then(onExecuted, onError);

This example executes a script from a file (packaged with the extension) called "content-script.js". The script is executed in the tab with an ID of 2:

function onExecuted(result) {
  console.log(`We executed in tab 2`);
}

function onError(error) {
  console.log(`Error: ${error}`);
}

const executing = browser.tabs.executeScript(2, {
  file: "/content-script.js",
});
executing.then(onExecuted, onError);

{{WebExtExamples}} 

Browser compatibility

{{Compat}} 

[!NOTE] This API is based on Chromium’s chrome.tabs API. This documentation is derived from tabs.json in the Chromium code.