An event handler that will be called repeatedly when response data is available. The handler is passed an event
object which contains a data
property, which contains a chunk of the response data as an ArrayBuffer
.
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Chrome | Edge | Firefox | Firefox for Android | Opera | |
---|---|---|---|---|---|
Basic support | No | No | 57 | 57 | No |
Examples
This example adds an ondata
listener which replaces "Example" in the response with "WebExtension Example".
Note that this example only works for occurrences of "Example" that are entirely contained within a data chunk, and not ones that straddle two chunks (which might happen ~0.1% of the time for large documents). Additionally it only deals with UTF-8-coded documents. A real implementation of this would have to be more complex.
function listener(details) { let filter = browser.webRequest.filterResponseData(details.requestId); let decoder = new TextDecoder("utf-8"); let encoder = new TextEncoder(); filter.ondata = event => { let str = decoder.decode(event.data, {stream: true}); // Just change any instance of Example in the HTTP response // to WebExtension Example. str = str.replace(/Example/g, 'WebExtension Example'); filter.write(encoder.encode(str)); // Doing filter.disconnect(); here would make us process only // the first chunk, and let the rest through unchanged. Note // that this would break multi-byte characters that occur on // the chunk boundary! } return {}; } browser.webRequest.onBeforeRequest.addListener( listener, {urls: ["https://example.com/*"], types: ["main_frame"]}, ["blocking"] );