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authorPeter Bengtsson <mail@peterbe.com>2020-12-08 14:42:17 -0500
committerPeter Bengtsson <mail@peterbe.com>2020-12-08 14:42:17 -0500
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+---
+title: Array.from()
+slug: Web/JavaScript/Reference/Global_Objects/Array/from
+translation_of: Web/JavaScript/Reference/Global_Objects/Array/from
+---
+<div>{{JSRef}}</div>
+
+<p>Method <code><strong>Array.from()</strong></code> membuat sebuah instansi <code>Array</code> dari sebuah array-like atau objek iterable.</p>
+
+<p>Di ES6, sintaks class memungkinkan untuk subclassing diantaranya built-in dan user defined classes; hasilnya , method statik class-side seperti <code><strong>Array.from</strong></code>  "diwariskan" oleh subclasses dari <code><strong>Array</strong></code> dan membuat instansi baru dari subclass, bukan <code><strong>Array</strong></code>.</p>
+
+<h2 id="Sintaks">Sintaks</h2>
+
+<pre class="syntaxbox"><code>Array.from(arrayLike[, mapFn[, thisArg]])
+</code></pre>
+
+<h3 id="Parameter">Parameter</h3>
+
+<dl>
+ <dt><code>arrayLike</code></dt>
+ <dd> Array-like atau objek iterable untuk diubah menjadi array.</dd>
+ <dt><code>mapFn</code></dt>
+ <dd>Opsional. Fungsi Map untuk memanggil setiap elemen array.</dd>
+ <dt><code>thisArg</code></dt>
+ <dd>Opsional. Nilai untuk digunakan <code>this</code> ketika mengeksekusi <code>mapFn</code>.</dd>
+</dl>
+
+<h2 id="Deskripsi">Deskripsi</h2>
+
+<p><code>Array.from()</code> memungkinkan anda membuat <code>Arrays</code> dari:</p>
+
+<ul>
+ <li>Objek array-like (objek dengan peoperti <code>length</code> dan elemen yang diindex) atau</li>
+ <li><a href="/en-US/docs/Web/JavaScript/Guide/iterable">Objek iterable</a> (objek dimana anda bisa mengambil elemen, seperti {{jsxref("Map")}} dan {{jsxref("Set")}}).</li>
+</ul>
+
+<p><code>Array.from()</code> memiliki parameter opsional <code>mapFn</code>, yang memungkinkan anda untuk mengeksekusi fungsi {{jsxref("Array.prototype.map", "map")}} pada setiap elemen array (atau objek subclass) yang akan dibuat. Jelasnya,<code> Array.from(obj, mapFn, thisArg)</code> sama dengan <code>Array.from(obj).map(mapFn, thisArg)</code>, kecuali dengan tidak membuat array menengah. Ini sangat penting untuk setiap subclass array, seperti <a href="/en-US/docs/Web/JavaScript/Typed_arrays">typed arrays</a>, selama array menengah akan memiliki nilai yang terpisah agar bisa masuk ke tipe yang sesuai.</p>
+
+<p>Properti <code>length</code> dari method <code>from()</code> adalah 1.</p>
+
+<h2 id="Contoh">Contoh</h2>
+
+<pre class="brush: js">// Array-like object (arguments) to Array
+function f() {
+ return Array.from(arguments);
+}
+
+f(1, 2, 3);
+// [1, 2, 3]
+
+
+// Any iterable object...
+// Set
+var s = new Set(["foo", window]);
+Array.from(s);
+// ["foo", window]
+
+
+// Map
+var m = new Map([[1, 2], [2, 4], [4, 8]]);
+Array.from(m);
+// [[1, 2], [2, 4], [4, 8]]
+
+
+// String
+Array.from("foo");
+// ["f", "o", "o"]
+
+
+// Using an arrow function as the map function to
+// manipulate the elements
+Array.from([1, 2, 3], x =&gt; x + x);
+// [2, 4, 6]
+
+
+// Generate a sequence of numbers
+Array.from({length: 5}, (v, k) =&gt; k);
+// [0, 1, 2, 3, 4]
+
+</pre>
+
+<h2 id="Polyfill">Polyfill</h2>
+
+<p><code>Array.from</code> telah di masukkan di standar ECMA-262 pada edisi ke-6; karena itu mungkin tidak bisa digunakan pada implementasi standar lain. Anda bisa menyiasatinya dengan menambahkan kode berikut ke awal script, memungkinkan penggunaan <code>Array.from</code> pada implementasi yang aslinya tidak mendukung.  Algoritma ini sama dengan yang di spesifikasikan di ECMA-262, edisi ke-6, dengan saumsi <code>Object</code> dan <code>TypeError</code> memiliki nilai tersendiri dan <code>callback.call</code> mengevaluasi nilai valur dari {{jsxref("Function.prototype.call")}}. Selain itu, sejak iterable tidak dapat di polyfill, implementasi ini tidak mendukung generik iterable seperti yang didefinisikan di edisi ke-6 di ECMA-262.</p>
+
+<pre class="brush: js">// Production steps of ECMA-262, Edition 6, 22.1.2.1
+// Reference: https://people.mozilla.org/~jorendorff/es6-draft.html#sec-array.from
+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 &gt; 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 &gt; 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 &gt; 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 &lt; len… (also steps a - h)
+ var kValue;
+ while (k &lt; 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;
+ };
+ }());
+}
+</pre>
+
+<h2 id="Spesifikasi">Spesifikasi</h2>
+
+<table class="standard-table">
+ <tbody>
+ <tr>
+ <th scope="col">Spesifikasi</th>
+ <th scope="col">Status</th>
+ <th scope="col">Comment</th>
+ </tr>
+ <tr>
+ <td>{{SpecName('ES6', '#sec-array.from', 'Array.from')}}</td>
+ <td>{{Spec2('ES6')}}</td>
+ <td>Initial definition.</td>
+ </tr>
+ <tr>
+ <td>{{SpecName('ESDraft', '#sec-array.from', 'Array.from')}}</td>
+ <td>{{Spec2('ESDraft')}}</td>
+ <td> </td>
+ </tr>
+ </tbody>
+</table>
+
+<h2 id="Kompabilitas_Browser">Kompabilitas Browser</h2>
+
+<div>{{CompatibilityTable}}</div>
+
+<div id="compat-desktop">
+<table class="compat-table">
+ <tbody>
+ <tr>
+ <th>Fitur</th>
+ <th>Chrome</th>
+ <th>Firefox (Gecko)</th>
+ <th>Edge</th>
+ <th>Internet Explorer</th>
+ <th>Opera</th>
+ <th>Safari</th>
+ </tr>
+ <tr>
+ <td>Dukungan dasar</td>
+ <td>{{CompatChrome("45")}}</td>
+ <td>{{CompatGeckoDesktop("32")}}</td>
+ <td>{{CompatVersionUnknown}}</td>
+ <td>{{CompatNo}}</td>
+ <td>{{CompatNo}}</td>
+ <td>9.0</td>
+ </tr>
+ </tbody>
+</table>
+</div>
+
+<div id="compat-mobile">
+<table class="compat-table">
+ <tbody>
+ <tr>
+ <th>Fitur</th>
+ <th>Android</th>
+ <th>Chrome for Android</th>
+ <th>Firefox Mobile (Gecko)</th>
+ <th>IE Mobile</th>
+ <th>Opera Mobile</th>
+ <th>Safari Mobile</th>
+ </tr>
+ <tr>
+ <td>Dukungan dasar</td>
+ <td>{{CompatNo}}</td>
+ <td>{{CompatNo}}</td>
+ <td>{{CompatGeckoMobile("32")}}</td>
+ <td>{{CompatNo}}</td>
+ <td>{{CompatNo}}</td>
+ <td>{{CompatNo}}</td>
+ </tr>
+ </tbody>
+</table>
+</div>
+
+<h2 id="Lihat_Juga">Lihat Juga</h2>
+
+<ul>
+ <li>{{jsxref("Array")}}</li>
+ <li>{{jsxref("Array.prototype.map()")}}</li>
+ <li>{{jsxref("TypedArray.from()")}}</li>
+</ul>