61 lines
1.7 KiB
JavaScript
61 lines
1.7 KiB
JavaScript
/**
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* @file
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* Provides a polyfill for Array.find().
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*
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* This is needed for Internet Explorer 11 and Opera Mini.
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*
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* This has been copied from MDN Web Docs code samples. Code samples in the MDN
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* Web Docs are licensed under CC0.
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*
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* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find#Polyfill
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* @see https://developer.mozilla.org/en-US/docs/MDN/About#Code_samples_and_snippets
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*/
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if (!Array.prototype.find) {
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Object.defineProperty(Array.prototype, 'find', {
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value: function (predicate) {
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// 1. Let O be ? ToObject(this value).
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if (this == null) {
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throw TypeError('"this" is null or not defined');
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}
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var o = Object(this);
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// 2. Let len be ? ToLength(? Get(O, "length")).
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var len = o.length >>> 0;
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// 3. If IsCallable(predicate) is false, throw a TypeError
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// exception.
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if (typeof predicate !== 'function') {
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throw TypeError('predicate must be a function');
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}
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// 4. If thisArg was supplied, let T be thisArg; else let T be
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// undefined.
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var thisArg = arguments[1];
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// 5. Let k be 0.
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var k = 0;
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// 6. Repeat, while k < len
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while (k < len) {
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// a. Let Pk be ! ToString(k).
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// b. Let kValue be ? Get(O, Pk).
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// c. Let testResult be ToBoolean(? Call(predicate, T, « kValue,
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// k, O »)).
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// d. If testResult is true, return kValue.
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var kValue = o[k];
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if (predicate.call(thisArg, kValue, k, o)) {
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return kValue;
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}
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// e. Increase k by 1.
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k++;
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}
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// 7. Return undefined.
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return undefined;
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},
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configurable: true,
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writable: true,
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});
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}
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