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[Bug]: listeners added via page.on("request", listener) can't be removed via"request", listener) #7572

fruttut opened this issue Sep 16, 2021 · 2 comments · Fixed by #7624


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@fruttut fruttut commented Sep 16, 2021

Bug description

Consider this snippet:

import puppeteer from "puppeteer";

(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto("", { waitUntil: ["load", "networkidle0"] });
await page.setRequestInterception(true);
const handler = (request) => {
  console.log("Handler invoked");
console.log(page.listenerCount("request")); // 0
page.on("request", handler);
console.log(page.listenerCount("request")); // 1"request", handler); // the listener is not removed
console.log(page.listenerCount("request")); // 1

This is very confusing in and of itself, but it gets much worse if I need to swap my request listener with another one later on:

const anotherHandler = (request) => {
  console.log("Another handler invoked");
 * When this handler is invoked and tries to process request with request.continue(), I get 
 * UnhandledPromiseRejectionWarning: Error: Request is already handled!
page.on("request", anotherHandler);

As far as I can see from the puppeteer code, it happens because in Page.ts the EventEmitter's on() method is overridden in such a way that, for request events, it creates a new callback and registers that callback as a listener instead of the one passed in the arguments.

Steps to reproduce the problem:

  1. Run the snippet above
  2. Observe the logs

Puppeteer version


Node.js version


npm version


What operating system are you seeing the problem on?


Relevant log output

No response

@fruttut fruttut added the bug label Sep 16, 2021
@fruttut fruttut changed the title [Bug]: listeners added via page.on("request", listener) can't be removed via"request", listener) [Bug]: listeners added via page.on("request", listener) can't be removed via"request", listener) Sep 16, 2021
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@JCMais JCMais commented Sep 21, 2021

having the same problem

@jschfflr jschfflr self-assigned this Sep 24, 2021
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@jschfflr jschfflr commented Sep 24, 2021

@fruttut Thanks for taking the time to report this issue!
I'll look into this :)

edgardmessias added a commit to edgardmessias/puppeteer that referenced this issue Oct 2, 2021
This patch fixes for request event

Issues: puppeteer#7572
@jschfflr jschfflr linked a pull request that will close this issue Oct 2, 2021
jschfflr pushed a commit that referenced this issue Oct 4, 2021
This patch fixes for request event

Closes: #7572
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3 participants