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Avoid extending built-in JS classes #175

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Merged
merged 2 commits into from
Oct 11, 2019
Merged

Avoid extending built-in JS classes #175

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077564c
Avoid extending Promise.
ghengeveld Oct 10, 2019
463c4b5
Fallback to setting __proto__.
ghengeveld Oct 10, 2019
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27 changes: 14 additions & 13 deletions packages/react-async/src/reducer.js
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Original file line number Diff line number Diff line change
@@ -1,25 +1,26 @@
import { getInitialStatus, getIdleStatus, getStatusProps, statusTypes } from "./status"

// This exists to make sure we don't hold any references to user-provided functions
class NeverSettle extends Promise {
constructor() {
super(() => {}, () => {})
/* istanbul ignore next */
if (Object.setPrototypeOf) {
// Not available in IE 10, but can be polyfilled
Object.setPrototypeOf(this, NeverSettle.prototype)
}
}
// The way NeverSettle extends from Promise is complicated, but can't be done differently because Babel doesn't support
// extending built-in classes. See https://babeljs.io/docs/en/caveats/#classes
function NeverSettle() {}
/* istanbul ignore next */
if (Object.setPrototypeOf) {
Object.setPrototypeOf(NeverSettle, Promise)
} else {
NeverSettle.__proto__ = Promise
}
NeverSettle.prototype = Object.assign(Object.create(Promise.prototype), {
finally() {
return this
}
},
catch() {
return this
}
},
then() {
return this
}
}
},
})

export const neverSettle = new NeverSettle()

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