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Report bad dead code elimination to React DevTools (#10702)
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* Report bad dead code elimination to React DevTools

* Fix lint
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gaearon authored Sep 13, 2017
1 parent c99bad9 commit aebd7f5
Showing 1 changed file with 31 additions and 0 deletions.
31 changes: 31 additions & 0 deletions packages/react-dom/index.js
Original file line number Diff line number Diff line change
@@ -1,6 +1,37 @@
'use strict';

function checkDCE() {
/* global __REACT_DEVTOOLS_GLOBAL_HOOK__ */
if (
typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ === 'undefined' ||
typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.checkDCE !== 'function'
) {
return;
}
if (process.env.NODE_ENV !== 'production') {
// This branch is unreachable because this function is only called
// in production, but the condition is true only in development.
// Therefore if the branch is still here, dead code elimination wasn't
// properly applied.
// Don't change the message. React DevTools relies on it. Also make sure
// this message doesn't occur elsewhere in this function, or it will cause
// a false positive.
throw new Error('^_^');
}
try {
// Verify that the code above has been dead code eliminated (DCE'd).
__REACT_DEVTOOLS_GLOBAL_HOOK__.checkDCE(checkDCE);
} catch (err) {
// DevTools shouldn't crash React, no matter what.
// We should still report in case we break this code.
console.error(err);
}
}

if (process.env.NODE_ENV === 'production') {
// DCE check should happen before ReactDOM bundle executes so that
// DevTools can report bad minification during injection.
checkDCE();
module.exports = require('./cjs/react-dom.production.min.js');
} else {
module.exports = require('./cjs/react-dom.development.js');
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