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August 25, 2023 14:04
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Qualtrics: Replace Qualtrics Array.from Polyfill with one that supports iterables #qualtrics #js #polyfill #array #from
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Qualtrics.SurveyEngine.addOnload(function() { | |
console.log(Array.from({length: 20}, (e, i) => i)); | |
}); | |
// Production steps of ECMA-262, Edition 6, 22.1.2.1 | |
// Copied and modified from http://www.devdoc.net/web/developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from.html | |
Array.from = (function () { | |
var toStr = Object.prototype.toString; | |
var isCallable = function (fn) { | |
return typeof fn === 'function' || toStr.call(fn) === '[object Function]'; | |
}; | |
var toInteger = function (value) { | |
var number = Number(value); | |
if (isNaN(number)) { return 0; } | |
if (number === 0 || !isFinite(number)) { return number; } | |
return (number > 0 ? 1 : -1) * Math.floor(Math.abs(number)); | |
}; | |
var maxSafeInteger = Math.pow(2, 53) - 1; | |
var toLength = function (value) { | |
var len = toInteger(value); | |
return Math.min(Math.max(len, 0), maxSafeInteger); | |
}; | |
// The length property of the from method is 1. | |
return function from(arrayLike/*, mapFn, thisArg */) { | |
// 1. Let C be the this value. | |
var C = this; | |
// 2. Let items be ToObject(arrayLike). | |
var items = Object(arrayLike); | |
// 3. ReturnIfAbrupt(items). | |
if (arrayLike == null) { | |
throw new TypeError('Array.from requires an array-like object - not null or undefined'); | |
} | |
// 4. If mapfn is undefined, then let mapping be false. | |
var mapFn = arguments.length > 1 ? arguments[1] : void undefined; | |
var T; | |
if (typeof mapFn !== 'undefined') { | |
// 5. else | |
// 5. a If IsCallable(mapfn) is false, throw a TypeError exception. | |
if (!isCallable(mapFn)) { | |
throw new TypeError('Array.from: when provided, the second argument must be a function'); | |
} | |
// 5. b. If thisArg was supplied, let T be thisArg; else let T be undefined. | |
if (arguments.length > 2) { | |
T = arguments[2]; | |
} | |
} | |
// 10. Let lenValue be Get(items, "length"). | |
// 11. Let len be ToLength(lenValue). | |
var len = toLength(items.length); | |
// 13. If IsConstructor(C) is true, then | |
// 13. a. Let A be the result of calling the [[Construct]] internal method | |
// of C with an argument list containing the single item len. | |
// 14. a. Else, Let A be ArrayCreate(len). | |
var A = isCallable(C) ? Object(new C(len)) : new Array(len); | |
// 16. Let k be 0. | |
var k = 0; | |
// 17. Repeat, while k < len… (also steps a - h) | |
var kValue; | |
while (k < len) { | |
kValue = items[k]; | |
if (mapFn) { | |
A[k] = typeof T === 'undefined' ? mapFn(kValue, k) : mapFn.call(T, kValue, k); | |
} else { | |
A[k] = kValue; | |
} | |
k += 1; | |
} | |
// 18. Let putStatus be Put(A, "length", len, true). | |
A.length = len; | |
// 20. Return A. | |
return A; | |
}; | |
}()); |
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