Suppose an add-on's job is to block web requests against a pattern, and the following scenario happens:
- The user loads a page that includes a particular request, and the pattern permits the request.
- The resource is loaded and cached in memory.
- The add-on's patterns are updated, in such a way that the resource would no longer be permitted.
- The user reloads the page.
Because the page will be reloaded from the memory cache, the listener may not be called again, and the request will be loaded despite the add-on's new policy.
The handlerBehaviorChanged() function is designed to address this problem. It flushes the in-memory cache, so that page reloads will trigger event listeners.
Because handlerBehaviorChanged() flushes the cache, it can be expensive and bad for performance. The webRequest module defines a read-only property MAX_HANDLER_BEHAVIOR_CHANGED_CALLS_PER_10_MINUTES: making more calls than this number in 10 minutes will have no effect.
The implementation of caching, hence the need for this function, varies from one browser to another, so in some browsers this function does nothing.
Syntax
browser.webRequest.handlerBehaviorChanged(
function() {...} // optional function
)
Parameters
callbackOptionalfunction.
Browser compatibility
Examples
This API is based on Chromium's chrome.webRequest API. This documentation is derived from web_request.json in the Chromium code.
// Copyright 2015 The Chromium Authors. All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following disclaimer // in the documentation and/or other materials provided with the // distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived from // this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
