37 lines
1.3 KiB
JavaScript
37 lines
1.3 KiB
JavaScript
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/**
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* Copyright 2013-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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*/
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'use strict';
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var _prodInvariant = require('./reactProdInvariant');
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var ReactElement = require('./ReactElement');
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var invariant = require('fbjs/lib/invariant');
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/**
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* Returns the first child in a collection of children and verifies that there
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* is only one child in the collection.
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*
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* See https://facebook.github.io/react/docs/top-level-api.html#react.children.only
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*
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* The current implementation of this function assumes that a single child gets
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* passed without a wrapper, but the purpose of this helper function is to
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* abstract away the particular structure of children.
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*
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* @param {?object} children Child collection structure.
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* @return {ReactElement} The first and only `ReactElement` contained in the
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* structure.
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*/
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function onlyChild(children) {
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!ReactElement.isValidElement(children) ? process.env.NODE_ENV !== 'production' ? invariant(false, 'React.Children.only expected to receive a single React element child.') : _prodInvariant('143') : void 0;
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return children;
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}
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module.exports = onlyChild;
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