Fired when a request could not be processed due to an error: for example, a lack of Internet connectivity.
The error is passed to the listener as the error
property of the details
object.
Note that this event is not fired for HTTP errors (4XX or 5XX responses): these will go through the normal stages of a request, calling any event listeners, and setting details.statusCode
to report the error.
This event is informational only.
Syntax
browser.webRequest.onErrorOccurred.addListener(function( details // object ) {...}) browser.webRequest.onErrorOccurred.removeListener(listener) browser.webRequest.onErrorOccurred.hasListener(listener)
Events have three functions:
addListener(callback, filter)
- Adds a listener to this event.
removeListener(listener)
- Stop listening to this event. The
listener
argument is the listener to remove. hasListener(listener)
- Check whether
listener
is registered for this event. Returnstrue
if it is listening,false
otherwise.
addListener syntax
Parameters
callback
-
A function that will be called when this event occurs. The function will be passed the following arguments:
filter
webRequest.RequestFilter
. A filter that restricts the events that will be sent to this listener.
Additional objects
details
requestId
string
. The ID of the request. Request IDs are unique within a browser session, so you can use them to relate different events associated with the same request.url
string
. Target of the request.method
string
. Standard HTTP method: for example, "GET" or "POST".frameId
integer
. Zero if the request happens in the main frame; a positive value is the ID of a subframe in which the request happens. If the document of a (sub-)frame is loaded (type
ismain_frame
orsub_frame
),frameId
indicates the ID of this frame, not the ID of the outer frame. Frame IDs are unique within a tab.parentFrameId
integer
. ID of the frame that contains the frame which sent the request. Set to -1 if no parent frame exists.tabId
integer
. The ID of the tab in which the request takes place. Set to -1 if the request isn't related to a tab.type
webRequest.ResourceType
. The type of resource being requested: for example, "image", "script", "stylesheet".timeStamp
number
. The time when this event fired, in milliseconds since the epoch.ip
Optionalstring
. The server IP address that the request was actually sent to. Note that it may be a literal IPv6 address.fromCache
boolean
. Indicates if this response was fetched from disk cache.error
string
. The error description. This string is an internal error string, may vary from one browser to another, and is not guaranteed to stay the same between releases.
Browser compatibility
Examples
var target = "<all_urls>"; /* e.g., with no network: "https://developer.mozilla.org/en-US/" NS_ERROR_NET_ON_RESOLVED in Firefox net::ERR_INTERNET_DISCONNECTED in Chrome */ function logError(responseDetails) { console.log(responseDetails.url); console.log(responseDetails.error); } chrome.webRequest.onErrorOccurred.addListener( logError, {urls: [target]} );
Acknowledgements
This API is based on Chromium's chrome.webRequest
API. This documentation is derived from web_request.json
in the Chromium code.
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