chrome.debugger

Description
The chrome.debugger API serves as an alternate transport for Chrome's remote debugging protocol. Use chrome.debugger to attach to one or more tabs to instrument network interaction, debug JavaScript, mutate the DOM and CSS, etc. Use the Debuggee tabId to target tabs with sendCommand and route events by tabId from onEvent callbacks.
Permissions
debugger

Notes #

As of today, attaching to the tab by means of the debugger API and using embedded Chrome DevTools with that tab are mutually exclusive. If user invokes Chrome DevTools while extension is attached to the tab, debugging session is terminated. Extension can re-establish it later.

Manifest #

You must declare the "debugger" permission in your extension's manifest to use this API.

{
  "name": "My extension",
  ...
  "permissions": [
    "debugger",
  ],
  ...
}

Examples #

You can find samples of this API in Samples.

Summary

Types
Debuggee
TargetInfo
DetachReason
TargetInfoType
Methods
attach
debugger.attach(target: Debuggee, requiredVersion: string, callback: function)
detach
debugger.detach(target: Debuggee, callback: function)
getTargets
debugger.getTargets(callback: function)
sendCommand
debugger.sendCommand(target: Debuggee, method: string, commandParams: object, callback: function)
Events
onDetach
onEvent

Types

Debuggee

Debuggee identifier. Either tabId or extensionId must be specified

Properties

extensionId
string optional
The id of the extension which you intend to debug. Attaching to an extension background page is only possible when 'silent-debugger-extension-api' flag is enabled on the target browser.
tabId
number optional
The id of the tab which you intend to debug.
targetId
string optional
The opaque id of the debug target.

TargetInfo

Debug target information

Properties

attached
boolean
True if debugger is already attached.
extensionId
string optional
The extension id, defined if type = 'background_page'.
faviconUrl
string optional
Target favicon URL.
id
string
Target id.
tabId
number optional
The tab id, defined if type == 'page'.
title
string
Target page title.
type
TargetInfoType
Target type.
url
string
Target URL.

DetachReason

Since Chrome 44.

Connection termination reason.

Enum

"target_closed", or "canceled_by_user"

TargetInfoType

Since Chrome 44.

Target type.

Enum

"page", "background_page", "worker", or "other"

Methods

attach

debugger.attach(target: Debuggee, requiredVersion: string, callback: function)

Attaches debugger to the given target.

Parameters

target
Debuggee
Debugging target to which you want to attach.
requiredVersion
string
Required debugging protocol version ("0.1"). One can only attach to the debuggee with matching major version and greater or equal minor version. List of the protocol versions can be obtained here.
callback
function
Called once the attach operation succeeds or fails. Callback receives no arguments. If the attach fails, runtime.lastError will be set to the error message.
The callback parameter should be a function that looks like this:
() => {...}

detach

debugger.detach(target: Debuggee, callback: function)

Detaches debugger from the given target.

Parameters

target
Debuggee
Debugging target from which you want to detach.
callback
function
Called once the detach operation succeeds or fails. Callback receives no arguments. If the detach fails, runtime.lastError will be set to the error message.
The callback parameter should be a function that looks like this:
() => {...}

getTargets

debugger.getTargets(callback: function)

Returns the list of available debug targets.

Parameters

callback
function
The callback parameter should be a function that looks like this:
(result: TargetInfo[]) => {...}
- result
  TargetInfo[]
  Array of TargetInfo objects corresponding to the available debug targets.

sendCommand

debugger.sendCommand(target: Debuggee, method: string, commandParams: object, callback: function)

Sends given command to the debugging target.

Parameters

target
Debuggee
Debugging target to which you want to send the command.
method
string
Method name. Should be one of the methods defined by the remote debugging protocol.
commandParams
object
JSON object with request parameters. This object must conform to the remote debugging params scheme for given method.
callback
function
Response body. If an error occurs while posting the message, the callback will be called with no arguments and runtime.lastError will be set to the error message.
The callback parameter should be a function that looks like this:
(result: object) => {...}
- result
  object
  JSON object with the response. Structure of the response varies depending on the method name and is defined by the 'returns' attribute of the command description in the remote debugging protocol.

Events

onDetach

debugger.onDetach.addListener(listener: function)

Fired when browser terminates debugging session for the tab. This happens when either the tab is being closed or Chrome DevTools is being invoked for the attached tab.

Event

listener
function
The listener parameter should be a function that looks like this:
(source: Debuggee, reason: DetachReason) => {...}
- source
  Debuggee
  The debuggee that was detached.
- reason
  DetachReason
  Connection termination reason.

onEvent

debugger.onEvent.addListener(listener: function)

Fired whenever debugging target issues instrumentation event.

Event

listener
function
The listener parameter should be a function that looks like this:
(source: Debuggee, method: string, params: object) => {...}
- source
  Debuggee
  The debuggee that generated this event.
- method
  string
  Method name. Should be one of the notifications defined by the remote debugging protocol.
- params
  object
  JSON object with the parameters. Structure of the parameters varies depending on the method name and is defined by the 'parameters' attribute of the event description in the remote debugging protocol.