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94 lines
2.6 KiB
94 lines
2.6 KiB
/** |
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* @source {https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from#Polyfill} |
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* but without thisArg (too hard to type, no need to `this`) |
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*/ |
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var toStr = Object.prototype.toString; |
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function isCallable(fn) { |
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return typeof fn === "function" || toStr.call(fn) === "[object Function]"; |
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} |
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function toInteger(value) { |
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var number = Number(value); |
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if (isNaN(number)) { |
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return 0; |
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} |
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if (number === 0 || !isFinite(number)) { |
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return number; |
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} |
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return (number > 0 ? 1 : -1) * Math.floor(Math.abs(number)); |
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} |
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var maxSafeInteger = Math.pow(2, 53) - 1; |
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function toLength(value) { |
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var len = toInteger(value); |
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return Math.min(Math.max(len, 0), maxSafeInteger); |
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} |
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/** |
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* Creates an array from an iterable object. |
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* @param iterable An iterable object to convert to an array. |
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*/ |
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/** |
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* Creates an array from an iterable object. |
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* @param iterable An iterable object to convert to an array. |
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* @param mapfn A mapping function to call on every element of the array. |
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* @param thisArg Value of 'this' used to invoke the mapfn. |
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*/ |
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export default function arrayFrom(arrayLike, mapFn) { |
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// 1. Let C be the this value. |
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// edit(@eps1lon): we're not calling it as Array.from |
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var C = Array; // 2. Let items be ToObject(arrayLike). |
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var items = Object(arrayLike); // 3. ReturnIfAbrupt(items). |
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if (arrayLike == null) { |
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throw new TypeError("Array.from requires an array-like object - not null or undefined"); |
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} // 4. If mapfn is undefined, then let mapping be false. |
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// const mapFn = arguments.length > 1 ? arguments[1] : void undefined; |
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if (typeof mapFn !== "undefined") { |
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// 5. else |
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// 5. a If IsCallable(mapfn) is false, throw a TypeError exception. |
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if (!isCallable(mapFn)) { |
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throw new TypeError("Array.from: when provided, the second argument must be a function"); |
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} |
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} // 10. Let lenValue be Get(items, "length"). |
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// 11. Let len be ToLength(lenValue). |
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var len = toLength(items.length); // 13. If IsConstructor(C) is true, then |
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// 13. a. Let A be the result of calling the [[Construct]] internal method |
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// of C with an argument list containing the single item len. |
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// 14. a. Else, Let A be ArrayCreate(len). |
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var A = isCallable(C) ? Object(new C(len)) : new Array(len); // 16. Let k be 0. |
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var k = 0; // 17. Repeat, while k < len… (also steps a - h) |
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var kValue; |
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while (k < len) { |
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kValue = items[k]; |
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if (mapFn) { |
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A[k] = mapFn(kValue, k); |
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} else { |
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A[k] = kValue; |
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} |
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k += 1; |
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} // 18. Let putStatus be Put(A, "length", len, true). |
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A.length = len; // 20. Return A. |
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return A; |
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} |
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//# sourceMappingURL=array.from.mjs.map
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