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https://github.com/facebook/react.git
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Andrew Clark
d9659e499e
Removes support for using arbitrary promises as the type of a React
element. Instead, promises must be wrapped in React.lazy. This gives us
flexibility later if we need to change the protocol.
The reason is that promises do not provide a way to call their
constructor multiple times. For example:
const promiseForA = new Promise(resolve => {
fetchA(a => resolve(a));
});
Given a reference to `promiseForA`, there's no way to call `fetchA`
again. Calling `then` on the promise doesn't run the constructor again;
it only attaches another listener.
In the future we will likely introduce an API like `React.eager` that
is similar to `lazy` but eagerly calls the constructor. That gives us
the ability to call the constructor multiple times. E.g. to increase
the priority, or to retry if the first operation failed.
42 lines
1.2 KiB
JavaScript
42 lines
1.2 KiB
JavaScript
/**
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @flow
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*/
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import {
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REACT_CONCURRENT_MODE_TYPE,
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REACT_CONTEXT_TYPE,
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REACT_FORWARD_REF_TYPE,
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REACT_FRAGMENT_TYPE,
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REACT_PROFILER_TYPE,
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REACT_PROVIDER_TYPE,
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REACT_STRICT_MODE_TYPE,
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REACT_SUSPENSE_TYPE,
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REACT_PURE_TYPE,
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REACT_LAZY_TYPE,
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} from 'shared/ReactSymbols';
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export default function isValidElementType(type: mixed) {
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return (
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typeof type === 'string' ||
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typeof type === 'function' ||
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// Note: its typeof might be other than 'symbol' or 'number' if it's a polyfill.
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type === REACT_FRAGMENT_TYPE ||
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type === REACT_CONCURRENT_MODE_TYPE ||
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type === REACT_PROFILER_TYPE ||
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type === REACT_STRICT_MODE_TYPE ||
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type === REACT_SUSPENSE_TYPE ||
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(typeof type === 'object' &&
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type !== null &&
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(type.$$typeof === REACT_LAZY_TYPE ||
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type.$$typeof === REACT_PURE_TYPE ||
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type.$$typeof === REACT_PROVIDER_TYPE ||
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type.$$typeof === REACT_CONTEXT_TYPE ||
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type.$$typeof === REACT_FORWARD_REF_TYPE))
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);
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}
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