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diff --git a/files/tr/web/javascript/reference/global_objects/map/index.html b/files/tr/web/javascript/reference/global_objects/map/index.html deleted file mode 100644 index 67f46594f6..0000000000 --- a/files/tr/web/javascript/reference/global_objects/map/index.html +++ /dev/null @@ -1,207 +0,0 @@ ---- -title: Map -slug: Web/JavaScript/Reference/Global_Objects/Map -tags: - - ECMAScript 2015 - - JavaScript - - Map - - NeedsTranslation - - TopicStub -translation_of: Web/JavaScript/Reference/Global_Objects/Map ---- -<div>{{JSRef}}</div> - -<p><span class="seoSummary">The <strong><code>Map</code></strong> object holds key-value pairs.</span> Any value (both objects and {{Glossary("Primitive", "primitive values")}}) may be used as either a key or a value.</p> - -<h2 id="Syntax">Syntax</h2> - -<pre class="syntaxbox">new Map([<em>iterable</em>])</pre> - -<h3 id="Parameters">Parameters</h3> - -<dl> - <dt><code>iterable</code></dt> - <dd>An {{jsxref("Array")}} or other <a href="/en-US/docs/Web/JavaScript/Guide/iterable">iterable</a> object whose elements are key-value pairs (arrays with two elements, e.g. <code>[[ 1, 'one' ],[ 2, 'two' ]]</code>). Each key-value pair is added to the new <code>Map</code>; <code>null</code> values are treated as <code>undefined</code>.</dd> -</dl> - -<h2 id="Description">Description</h2> - -<p>A <code>Map</code> object iterates its elements in insertion order — a {{jsxref("Statements/for...of", "for...of")}} loop returns an array of <code>[key, value]</code> for each iteration.<br> - <br> - It should be noted that a <code>Map</code> which is a map of an object, especially a dictionary of dictionaries, will only map to the object's insertion order—which is random and not ordered.</p> - -<h3 id="Key_equality">Key equality</h3> - -<p>Key equality is based on the "SameValueZero" algorithm: <code>NaN</code> is considered the same as <code>NaN</code> (even though <code>NaN !== NaN</code>) and all other values are considered equal according to the semantics of the <code>===</code> operator. In the current ECMAScript specification <code>-0</code> and <code>+0</code> are considered equal, although this was not so in earlier drafts. See "Value equality for -0 and 0" in the <a href="#Browser_compatibility">browser compatibility</a> table for details.</p> - -<h3 id="Objects_and_maps_compared">Objects and maps compared</h3> - -<p>{{jsxref("Object", "Objects")}} are similar to <code>Maps</code> in that both let you set keys to values, retrieve those values, delete keys, and detect whether something is stored at a key. Because of this (and because there were no built-in alternatives), <code>Object</code>s have been used as <code>Maps</code> historically; however, there are important differences that make using a <code>Map</code> preferable in certain cases:</p> - -<ul> - <li>The keys of an <code>Object</code> are {{jsxref("String", "Strings")}} and {{jsxref("Symbol", "Symbols")}}, whereas they can be any value for a <code>Map</code>, including functions, objects, and any primitive.</li> - <li>You can get the size of a <code>Map</code> easily with the <code>size</code> property, while the number of properties in an <code>Object</code> must be determined manually.</li> - <li>A <code>Map</code> is an <a href="/en-US/docs/Web/JavaScript/Guide/iterable">iterable</a> and can thus be directly iterated, whereas iterating over an <code>Object</code> requires obtaining its keys in some fashion and iterating over them.</li> - <li>An <code>Object</code> has a prototype, so there are default keys in the map that could collide with your keys if you're not careful. As of ES5 this can be bypassed by using <code>map = Object.create(null)</code>, but this is seldom done.</li> - <li>A <code>Map</code> may perform better in scenarios involving frequent addition and removal of key pairs.</li> -</ul> - -<h2 id="Properties">Properties</h2> - -<dl> - <dt><code>Map.length</code></dt> - <dd>The value of the <code>length</code> property is 0.</dd> - <dt>{{jsxref("Map.@@species", "get Map[@@species]")}}</dt> - <dd>The constructor function that is used to create derived objects.</dd> - <dt>{{jsxref("Map.prototype")}}</dt> - <dd>Represents the prototype for the <code>Map</code> constructor. Allows the addition of properties to all <code>Map</code> objects.</dd> -</dl> - -<h2 id="Map_instances"><code>Map</code> instances</h2> - -<p>All <code>Map</code> instances inherit from {{jsxref("Map.prototype")}}.</p> - -<h3 id="Properties_2">Properties</h3> - -<p>{{page('en-US/Web/JavaScript/Reference/Global_Objects/Map/prototype','Properties')}}</p> - -<h3 id="Methods">Methods</h3> - -<p>{{page('en-US/Web/JavaScript/Reference/Global_Objects/Map/prototype','Methods')}}</p> - -<h2 id="Examples">Examples</h2> - -<h3 id="Using_the_Map_object">Using the <code>Map</code> object</h3> - -<pre class="brush: js">var myMap = new Map(); - -var keyString = 'a string', - keyObj = {}, - keyFunc = function() {}; - -// setting the values -myMap.set(keyString, "value associated with 'a string'"); -myMap.set(keyObj, 'value associated with keyObj'); -myMap.set(keyFunc, 'value associated with keyFunc'); - -myMap.size; // 3 - -// getting the values -myMap.get(keyString); // "value associated with 'a string'" -myMap.get(keyObj); // "value associated with keyObj" -myMap.get(keyFunc); // "value associated with keyFunc" - -myMap.get('a string'); // "value associated with 'a string'" - // because keyString === 'a string' -myMap.get({}); // undefined, because keyObj !== {} -myMap.get(function() {}) // undefined, because keyFunc !== function () {} -</pre> - -<h3 id="Using_NaN_as_Map_keys">Using <code>NaN</code> as <code>Map</code> keys</h3> - -<p><code>NaN</code> can also be used as a key. Even though every <code>NaN</code> is not equal to itself (<code>NaN !== NaN</code> is true), the following example works because <code>NaN</code>s are indistinguishable from each other:</p> - -<pre class="brush: js">var myMap = new Map(); -myMap.set(NaN, 'not a number'); - -myMap.get(NaN); // "not a number" - -var otherNaN = Number('foo'); -myMap.get(otherNaN); // "not a number" -</pre> - -<h3 id="Iterating_Maps_with_for..of">Iterating <code>Maps</code> with <code>for..of</code></h3> - -<p>Maps can be iterated using a <code>for..of</code> loop:</p> - -<pre class="brush: js">var myMap = new Map(); -myMap.set(0, 'zero'); -myMap.set(1, 'one'); -for (var [key, value] of myMap) { - console.log(key + ' = ' + value); -} -// 0 = zero -// 1 = one - -for (var key of myMap.keys()) { - console.log(key); -} -// 0 -// 1 - -for (var value of myMap.values()) { - console.log(value); -} -// zero -// one - -for (var [key, value] of myMap.entries()) { - console.log(key + ' = ' + value); -} -// 0 = zero -// 1 = one -</pre> - -<h3 id="Iterating_Maps_with_forEach()">Iterating <code>Maps</code> with <code>forEach()</code></h3> - -<p>Maps can be iterated using the <code>forEach()</code> method:</p> - -<pre class="brush: js">myMap.forEach(function(value, key) { - console.log(key + ' = ' + value); -}); -// Will show 2 logs; first with "0 = zero" and second with "1 = one" -</pre> - -<h3 id="Relation_with_Array_objects">Relation with <code>Array</code> objects</h3> - -<pre class="brush: js">var kvArray = [['key1', 'value1'], ['key2', 'value2']]; - -// Use the regular Map constructor to transform a 2D key-value Array into a map -var myMap = new Map(kvArray); - -myMap.get('key1'); // returns "value1" - -// Use the Array.from function to transform a map into a 2D key-value Array -console.log(Array.from(myMap)); // Will show you exactly the same Array as kvArray - -// Or use the keys or values iterators and convert them to an array -console.log(Array.from(myMap.keys())); // Will show ["key1", "key2"] -</pre> - -<h2 id="Specifications">Specifications</h2> - -<table class="standard-table"> - <tbody> - <tr> - <th scope="col">Specification</th> - <th scope="col">Status</th> - <th scope="col">Comment</th> - </tr> - <tr> - <td>{{SpecName('ES2015', '#sec-map-objects', 'Map')}}</td> - <td>{{Spec2('ES2015')}}</td> - <td>Initial definition.</td> - </tr> - <tr> - <td>{{SpecName('ESDraft', '#sec-map-objects', 'Map')}}</td> - <td>{{Spec2('ESDraft')}}</td> - <td> </td> - </tr> - </tbody> -</table> - -<h2 id="Browser_compatibility">Browser compatibility</h2> - - - -<p>{{Compat("javascript.builtins.Map")}}</p> - -<h2 id="See_also">See also</h2> - -<ul> - <li><a class="link-https" href="https://bugzilla.mozilla.org/show_bug.cgi?id=697479">Map and Set bug at Mozilla</a></li> - <li><a class="external" href="http://wiki.ecmascript.org/doku.php?id=harmony:simple_maps_and_sets">ECMAScript Harmony proposal</a></li> - <li>{{jsxref("Set")}}</li> - <li>{{jsxref("WeakMap")}}</li> - <li>{{jsxref("WeakSet")}}</li> -</ul> |