chrome.devtools.inspectedWindow

Description

Use the chrome.devtools.inspectedWindow API to interact with the inspected window: obtain the tab ID for the inspected page, evaluate the code in the context of the inspected window, reload the page, or obtain the list of resources within the page.

Manifest

The following keys must be declared in the manifest to use this API.

"devtools_page"

Use chrome.devtools.inspectedWindow to interact with the inspected window: obtain the tab ID for the inspected page, evaluate the code in the context of inspected window, reload the page, or obtain the list of resources within the page.

See DevTools APIs summary for general introduction to using Developer Tools APIs.

Overview

The tabId property provides the tab identifier that you can use with the chrome.tabs.* API calls. However, please note that chrome.tabs.* API is not exposed to the Developer Tools extension pages due to security considerations—you will need to pass the tab ID to the background page and invoke the chrome.tabs.* API functions from there.

The reload method may be used to reload the inspected page. Additionally, the caller can specify an override for the user agent string, a script that will be injected early upon page load, or an option to force reload of cached resources.

Use the getResources call and the onResourceContent event to obtain the list of resources (documents, stylesheets, scripts, images etc) within the inspected page. The getContent and setContent methods of the Resource class along with the onResourceContentCommitted event may be used to support modification of the resource content, for example, by an external editor.

Executing Code in the Inspected Window

The eval method provides the ability for extensions to execute JavaScript code in the context of the inspected page. This method is powerful when used in the right context and dangerous when used inappropriately. Use the tabs.executeScript method unless you need the specific functionality that the eval method provides.

Here are the main differences between the eval and tabs.executeScript methods:

  • The eval method does not use an isolated world for the code being evaluated, so the JavaScript state of the inspected window is accessible to the code. Use this method when access to the JavaScript state of the inspected page is required.
  • The execution context of the code being evaluated includes the Developer Tools console API. For example, the code can use inspect and $0.
  • The evaluated code may return a value that is passed to the extension callback. The returned value has to be a valid JSON object (it may contain only primitive JavaScript types and acyclic references to other JSON objects). Please observe extra care while processing the data received from the inspected page—the execution context is essentially controlled by the inspected page; a malicious page may affect the data being returned to the extension.

Note that a page can include multiple different JavaScript execution contexts. Each frame has its own context, plus an additional context for each extension that has content scripts running in that frame.

By default, the eval method executes in the context of the main frame of the inspected page.

The eval method takes an optional second argument that you can use to specify the context in which the code is evaluated. This options object can contain one or more of the following keys:

frameURL
Use to specify a frame other than the inspected page's main frame.
contextSecurityOrigin
Use to select a context within the specified frame according to its web origin.
useContentScriptContext
If true, execute the script in the same context as the extensions's content scripts. (Equivalent to specifying the extensions's own web orgin as the context security origin.) This can be used to exchange data with the content script.

Examples

The following code checks for the version of jQuery used by the inspected page:

chrome.devtools.inspectedWindow.eval(
  "jQuery.fn.jquery",
  function(result, isException) {
    if (isException) {
      console.log("the page is not using jQuery");
    } else {
      console.log("The page is using jQuery v" + result);
    }
  }
);

To try this API, install the devtools API examples from the chrome-extension-samples repository.

Types

Resource

A resource within the inspected page, such as a document, a script, or an image.

Properties

  • url

    string

    The URL of the resource.

  • getContent

    void

    Gets the content of the resource.

    The getContent function looks like: 

    (callback: function) => {...}

    • callback

      function

      The callback parameter looks like: 

      (content: string, encoding: string) => void

      • content

        string

        Content of the resource (potentially encoded).

      • encoding

        string

        Empty if the content is not encoded, encoding name otherwise. Currently, only base64 is supported.

  • setContent

    void

    Sets the content of the resource.

    The setContent function looks like: 

    (content: string, commit: boolean, callback?: function) => {...}

    • content

      string

      New content of the resource. Only resources with the text type are currently supported.

    • commit

      boolean

      True if the user has finished editing the resource, and the new content of the resource should be persisted; false if this is a minor change sent in progress of the user editing the resource.

    • callback

      function optional

      The callback parameter looks like: 

      (error?: object) => void

      • error

        object optional

        Set to undefined if the resource content was set successfully; describes error otherwise.

Properties

tabId

The ID of the tab being inspected. This ID may be used with chrome.tabs.* API.

Type

number

Methods

eval()

chrome.devtools.inspectedWindow.eval(
  expression: string,
  options?: object,
  callback?: function,
)

Evaluates a JavaScript expression in the context of the main frame of the inspected page. The expression must evaluate to a JSON-compliant object, otherwise an exception is thrown. The eval function can report either a DevTools-side error or a JavaScript exception that occurs during evaluation. In either case, the result parameter of the callback is undefined. In the case of a DevTools-side error, the isException parameter is non-null and has isError set to true and code set to an error code. In the case of a JavaScript error, isException is set to true and value is set to the string value of thrown object.

Parameters

  • expression

    string

    An expression to evaluate.

  • options

    object optional

    The options parameter can contain one or more options.

    • frameURL

      string optional

      If specified, the expression is evaluated on the iframe whose URL matches the one specified. By default, the expression is evaluated in the top frame of the inspected page.

    • scriptExecutionContext

      string optional

      Chrome 107+

      Evaluate the expression in the context of a content script of an extension that matches the specified origin. If given, scriptExecutionContext overrides the 'true' setting on useContentScriptContext.

    • useContentScriptContext

      boolean optional

      Evaluate the expression in the context of the content script of the calling extension, provided that the content script is already injected into the inspected page. If not, the expression is not evaluated and the callback is invoked with the exception parameter set to an object that has the isError field set to true and the code field set to E_NOTFOUND.

  • callback

    function optional

    The callback parameter looks like: 

    (result: object, exceptionInfo: object) => void

    • result

      object

      The result of evaluation.

    • exceptionInfo

      object

      An object providing details if an exception occurred while evaluating the expression.

      • code

        string

        Set if the error occurred on the DevTools side before the expression is evaluated.

      • description

        string

        Set if the error occurred on the DevTools side before the expression is evaluated.

      • details

        any[]

        Set if the error occurred on the DevTools side before the expression is evaluated, contains the array of the values that may be substituted into the description string to provide more information about the cause of the error.

      • isError

        boolean

        Set if the error occurred on the DevTools side before the expression is evaluated.

      • isException

        boolean

        Set if the evaluated code produces an unhandled exception.

      • value

        string

        Set if the evaluated code produces an unhandled exception.

getResources()

chrome.devtools.inspectedWindow.getResources(
  callback: function,
)

Retrieves the list of resources from the inspected page.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (resources: Resource[]) => void

    • resources

      Resource[]

      The resources within the page.

reload()

chrome.devtools.inspectedWindow.reload(
  reloadOptions?: object,
)

Reloads the inspected page.

Parameters

  • reloadOptions

    object optional

    • ignoreCache

      boolean optional

      When true, the loader will bypass the cache for all inspected page resources loaded before the load event is fired. The effect is similar to pressing Ctrl+Shift+R in the inspected window or within the Developer Tools window.

    • injectedScript

      string optional

      If specified, the script will be injected into every frame of the inspected page immediately upon load, before any of the frame's scripts. The script will not be injected after subsequent reloads—for example, if the user presses Ctrl+R.

    • userAgent

      string optional

      If specified, the string will override the value of the User-Agent HTTP header that's sent while loading the resources of the inspected page. The string will also override the value of the navigator.userAgent property that's returned to any scripts that are running within the inspected page.

Events

onResourceAdded

chrome.devtools.inspectedWindow.onResourceAdded.addListener(
  callback: function,
)

Fired when a new resource is added to the inspected page.

Parameters

  • callback

    function

    The callback parameter looks like: 

    (resource: Resource) => void

onResourceContentCommitted

chrome.devtools.inspectedWindow.onResourceContentCommitted.addListener(
  callback: function,
)

Fired when a new revision of the resource is committed (e.g. user saves an edited version of the resource in the Developer Tools).

Parameters

  • callback

    function

    The callback parameter looks like: 

    (resource: Resource, content: string) => void