mirror of
https://github.com/facebook/react.git
synced 2025-11-01 09:12:30 +00:00
Tim Yung
59 lines
1.5 KiB
JavaScript
59 lines
1.5 KiB
JavaScript
/**
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* Copyright 2013 Facebook, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* @providesModule keyMirror
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* @typechecks static-only
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*/
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"use strict";
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var invariant = require('invariant');
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/**
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* Constructs an enumeration with keys equal to their value.
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*
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* For example:
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*
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* var COLORS = keyMirror({blue: null, red: null});
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* var myColor = COLORS.blue;
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* var isColorValid = !!COLORS[myColor];
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*
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* The last line could not be performed if the values of the generated enum were
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* not equal to their keys.
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*
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* Input: {key1: val1, key2: val2}
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* Output: {key1: key1, key2: key2}
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*
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* @param {object} obj
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* @return {object}
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*/
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var keyMirror = function(obj) {
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var ret = {};
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var key;
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invariant(
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obj instanceof Object && !Array.isArray(obj),
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'keyMirror(...): Argument must be an object.'
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);
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for (key in obj) {
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if (!obj.hasOwnProperty(key)) {
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continue;
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}
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ret[key] = key;
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}
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return ret;
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};
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module.exports = keyMirror;
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