--- title: Array.from() slug: Web/JavaScript/Reference/Global_Objects/Array/from translation_of: Web/JavaScript/Reference/Global_Objects/Array/from ---
Array.from()
metodu bir dizi-benzeri veya gezinilebilir bir nesneden yeni bir Dizi örneği oluşturur.
Array.from("birşey"); // ["b", "i", "r", "ş", "e", "y"]
Array.from(arrayLike[, mapFn[, thisArg]])
arrayLike
mapFn
thisArg
mapFn fonksiyonu işletilirken kullanılacak olan this argüman değeridir.
Yeni bir {{jsxref("Array")}} örneği.
Array.from(),
aşağıdaki yapılardan Diziler
oluşturmanıza izin verir:
length
) özelliği olan nesneler) ya daArray.from()
has an optional parameter mapFn
, which allows you to execute a {{jsxref("Array.prototype.map", "map")}} function on each element of the array (or subclass object) that is being created. More clearly, Array.from(obj, mapFn, thisArg)
has the same result as Array.from(obj).map(mapFn, thisArg)
, except that it does not create an intermediate array. This is especially important for certain array subclasses, like typed arrays, since the intermediate array would necessarily have values truncated to fit into the appropriate type.
The length
property of the from()
method is 1.
In ES2015, the class syntax allows for sub-classing of both built-in and user defined classes; as a result, static methods such as Array.from
are "inherited" by subclasses of Array
and create new instances of the subclass, not Array
.
Array.from("birşey"); // ["b", "i", "r", "ş", "e", "y"]
Set nesnesinden Dizi oluşturma
var s = new Set(["birşey", window]); Array.from(s); // ["birşey", window]
Map nesnesinden Dizi oluşturma
var m = new Map([[1, 2], [2, 4], [4, 8]]); Array.from(m); // [[1, 2], [2, 4], [4, 8]]
function f() { return Array.from(arguments); } f(1, 2, 3); // [1, 2, 3]
Array.from kullanma
// Bir işlevini, map işlevi olarak kullanıp // öğeler üzerinde oynama yapmak Array.from([1, 2, 3], x => x + x); // [2, 4, 6] // Generate a sequence of numbers // Since the array is initialized with `undefined` on each position, // the value of `v` below will be `undefined` Array.from({length: 5}, (v, i) => i); // [0, 1, 2, 3, 4]
Array.from
was added to the ECMA-262 standard in the 6th edition (ES2015); as such it may not be present in other implementations of the standard. You can work around this by inserting the following code at the beginning of your scripts, allowing use of Array.from
in implementations that don't natively support it. This algorithm is exactly the one specified in ECMA-262, 6th edition, assuming Object
and TypeError
have their original values and that callback.call
evaluates to the original value of {{jsxref("Function.prototype.call")}}. In addition, since true iterables can not be polyfilled, this implementation does not support generic iterables as defined in the 6th edition of ECMA-262.
// Production steps of ECMA-262, Edition 6, 22.1.2.1 if (!Array.from) { 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; }; }()); }
Specification | Status | Comment |
---|---|---|
{{SpecName('ES6', '#sec-array.from', 'Array.from')}} | {{Spec2('ES6')}} | Initial definition. |
{{SpecName('ESDraft', '#sec-array.from', 'Array.from')}} | {{Spec2('ESDraft')}} |
Feature | Chrome | Firefox (Gecko) | Edge | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | {{CompatChrome("45")}} | {{CompatGeckoDesktop("32")}} | {{CompatVersionUnknown}} | {{CompatNo}} | {{CompatVersionUnknown}} | 9.0 |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | {{CompatNo}} | {{CompatNo}} | {{CompatGeckoMobile("32")}} | {{CompatNo}} | {{CompatNo}} | {{CompatNo}} |