webNavigation.onBeforeNavigate

Fired when the browser is about to start a navigation event.

Syntax

browser.webNavigation.onBeforeNavigate.addListener(
  listener,                   // function
  filter                      // optional object
)
browser.webNavigation.onBeforeNavigate.removeListener(listener)
browser.webNavigation.onBeforeNavigate.hasListener(listener)

Events have three functions:

addListener(callback): 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. Returns true if it is listening, false otherwise.

addListener syntax

Parameters

callback

Function that will be called when this event occurs. The function will be passed the following arguments:

details: object. Details about the navigation event.

filterOptional

object. An object containing a single property url, which is an Array of events.UrlFilter objects. If you include this parameter, then the event will fire only for transitions to URLs which match at least one UrlFilter in the array. If you omit this parameter, the event will fire for all transitions.

Additional objects

details

tabId: integer. The ID of the tab in which the navigation is about to occur.
url: string. The URL to which the given frame will navigate.
processId: integer. The ID of the process in which this tab is being rendered (This property is not supported on Firefox and it is deprecated on Chrome).
frameId: integer. Frame in which the navigation is about to occur. 0 indicates that navigation happens in the tab's top-level browsing context, not in a nested iframe. A positive value indicates that navigation happens in a nested iframe. Frame IDs are unique for a given tab and process.
parentFrameId: integer. ID of this frame's parent. Set to -1 if this is a top-level frame.
timeStamp: number. The time when the browser is about to start the navigation, in milliseconds since the epoch.

Browser compatibility

	Chrome	Edge	Firefox	Firefox for Android	Opera
Basic support	Yes ¹	Yes ²	45 ³ ⁴	48 ³ ⁴	17 ⁵

1. If the filter parameter is empty, Chrome matches all URLs.
2. Filtering is not supported.
3. Filtering is supported from version 50.
4. If the filter parameter is empty, Firefox raises an exception.
5. If the filter parameter is empty, Opera matches all URLs.

Examples

Logs the target URLs for onBeforeNavigate, if the target's hostname contains "example.com" or starts with "developer".

var filter = {
  url:
  [
    {hostContains: "example.com"},
    {hostPrefix: "developer"}
  ]
}
function logOnBefore(details) {
  console.log("onBeforeNavigate to: " + details.url);
}
browser.webNavigation.onBeforeNavigate.addListener(logOnBefore, filter);

Acknowledgements

This API is based on Chromium's chrome.webNavigation API. This documentation is derived from web_navigation.json in the Chromium code.

Microsoft Edge compatibility data is supplied by Microsoft Corporation and is included here under the Creative Commons Attribution 3.0 United States License.

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