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DevTools bugfix: Ignore duplicate welcome "message" events #24186

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merged 1 commit into from
Mar 28, 2022
Merged

DevTools bugfix: Ignore duplicate welcome "message" events #24186

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21 changes: 21 additions & 0 deletions packages/react-devtools-extensions/src/backend.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,8 @@

'use strict';

let welcomeHasInitialized = false;

function welcome(event) {
if (
event.source !== window ||
Expand All @@ -14,6 +16,25 @@ function welcome(event) {
return;
}

// In some circumstances, this method is called more than once for a single welcome message.
// The exact circumstances of this are unclear, though it seems related to 3rd party event batching code.
//
// Regardless, call this method multiple times can cause DevTools to add duplicate elements to the Store
// (and throw an error) or worse yet, choke up entirely and freeze the browser.
//
// The simplest solution is to ignore the duplicate events.
// To be clear, this SHOULD NOT BE NECESSARY, since we remove the event handler below.
//
// See https://github.com/facebook/react/issues/24162
if (welcomeHasInitialized) {
console.warn(
'React DevTools detected duplicate welcome "message" events from the content script.',
);
return;
}

welcomeHasInitialized = true;

window.removeEventListener('message', welcome);
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The above change seems kind of silly, since we're removing the event handler here– but it seems like the batching (mentioned in the comment above) prevents the event handler from being removed properly.

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It looks like maybe the removeEventHandler part of the event handler API is being broken– such that we can register an event handler on the window but then never remove it. This is a pretty serious bug that should be fixed (somewhere in react-easy-state maybe?)


setup(window.__REACT_DEVTOOLS_GLOBAL_HOOK__);
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10 changes: 5 additions & 5 deletions packages/react-devtools-extensions/src/contentScript.js
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Original file line number Diff line number Diff line change
Expand Up @@ -25,15 +25,15 @@ function handleMessageFromDevtools(message) {
);
}

function handleMessageFromPage(evt) {
function handleMessageFromPage(event) {
if (
evt.source === window &&
evt.data &&
evt.data.source === 'react-devtools-bridge'
event.source === window &&
event.data &&
event.data.source === 'react-devtools-bridge'
) {
backendInitialized = true;

port.postMessage(evt.data.payload);
port.postMessage(event.data.payload);
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This change wasn't necessary, the name evt just irked me.

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😂

}
}

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