54 lines
1.5 KiB
TypeScript
54 lines
1.5 KiB
TypeScript
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/* eslint @typescript-eslint/no-explicit-any: "off" */
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/**
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* Polyfills the `Array.prototype.reduce` method.
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*
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* Production steps of ECMA-262, Edition 5, 15.4.4.21
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* Reference: https://es5.github.io/#x15.4.4.21
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* https://tc39.github.io/ecma262/#sec-array.prototype.reduce
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*
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*/
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export function setArrayPrototypeReduce(): void {
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Object.defineProperty(Array.prototype, "reduce", {
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value: function (...args: any) {
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const callback = args[0];
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if (this === null) {
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throw new TypeError(
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"Array.prototype.reduce called on null or undefined"
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);
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}
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if (typeof callback !== "function") {
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throw new TypeError(`${callback} is not a function`);
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}
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const o = Object(this);
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const len = o.length >>> 0;
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let k = 0;
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let value;
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if (args.length >= 2) {
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value = args[1];
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} else {
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while (k < len && !(k in o)) {
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k++;
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}
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if (k >= len) {
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throw new TypeError(
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"Reduce of empty array with no initial value"
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);
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}
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value = o[k++];
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}
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while (k < len) {
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if (k in o) {
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value = callback(value, o[k], k, o);
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}
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k++;
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}
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return value;
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},
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});
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}
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