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Diffstat (limited to 'node_modules/fbjs/lib/shallowEqual.js')
-rw-r--r-- | node_modules/fbjs/lib/shallowEqual.js | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/node_modules/fbjs/lib/shallowEqual.js b/node_modules/fbjs/lib/shallowEqual.js new file mode 100644 index 000000000..b7899474b --- /dev/null +++ b/node_modules/fbjs/lib/shallowEqual.js @@ -0,0 +1,67 @@ +/** + * Copyright (c) 2013-present, Facebook, Inc. + * All rights reserved. + * + * This source code is licensed under the BSD-style license found in the + * LICENSE file in the root directory of this source tree. An additional grant + * of patent rights can be found in the PATENTS file in the same directory. + * + * @typechecks + * + */ + +/*eslint-disable no-self-compare */ + +'use strict'; + +var hasOwnProperty = Object.prototype.hasOwnProperty; + +/** + * inlined Object.is polyfill to avoid requiring consumers ship their own + * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is + */ +function is(x, y) { + // SameValue algorithm + if (x === y) { + // Steps 1-5, 7-10 + // Steps 6.b-6.e: +0 != -0 + // Added the nonzero y check to make Flow happy, but it is redundant + return x !== 0 || y !== 0 || 1 / x === 1 / y; + } else { + // Step 6.a: NaN == NaN + return x !== x && y !== y; + } +} + +/** + * Performs equality by iterating through keys on an object and returning false + * when any key has values which are not strictly equal between the arguments. + * Returns true when the values of all keys are strictly equal. + */ +function shallowEqual(objA, objB) { + if (is(objA, objB)) { + return true; + } + + if (typeof objA !== 'object' || objA === null || typeof objB !== 'object' || objB === null) { + return false; + } + + var keysA = Object.keys(objA); + var keysB = Object.keys(objB); + + if (keysA.length !== keysB.length) { + return false; + } + + // Test for A's keys different from B. + for (var i = 0; i < keysA.length; i++) { + if (!hasOwnProperty.call(objB, keysA[i]) || !is(objA[keysA[i]], objB[keysA[i]])) { + return false; + } + } + + return true; +} + +module.exports = shallowEqual;
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