Revision 1069178 of static

<div>{{jsSidebar("Classes")}}</div>

<p>The <strong>static</strong> keyword defines a static method for a class.</p>

<h2 id="Syntax">Syntax</h2>

<pre class="syntaxbox">
static methodName() { ... }</pre>

<h2 id="Description">Description</h2>

<p>Static methods are called without instantiating their class and&nbsp;are also not&nbsp;callable when the class is instantiated. Static methods are often used to create utility functions for an application.</p>

<h2 id="Calling_static_method">Calling static method</h2>

<h3 id="From_another_static_method">From another static method</h3>

<p>In order to call another static method in static method you can simply use <a href="/en-US/docs/Web/JavaScript/Reference/Operators/this">this</a> keyword.</p>

<pre class="brush: js">
class StaticMethodCall {
    static staticMethod() {
        return 'Static method has been called';
    }
    static anotherStaticMethod() {
        return this.staticMethod() + ' from another static method';
    }
}
StaticMethodCall.staticMethod(); // 'Static method has been called'
StaticMethodCall.anotherStaticMethod(); // 'Static method has been called from another static method'</pre>

<h3 id="sect1">&nbsp;</h3>

<h3 id="From_class_constructor_and_other_methods">From class constructor and other methods</h3>

<p>As static method is part of class, it's not accessible through this keyword. the solution to the problem would be using of <code>CLASSNAME.STATIC_METHOD_NAME</code> (like other calls from outside of class) or <code>this.constructor.STATIC_METHOD_NAME</code>.</p>

<pre class="brush: js">
class StaticMethodCall{
    constructor(){
        console.log(StaticMethodCall.staticMethod()); // 'static method has been called' 
        console.log(this.constructor.staticMethod()); // 'static method has been called' 
    }

    static  staticMethod(){
        return 'static method has been called.';
    }
}</pre>

<h2 id="Examples">Examples</h2>

<p>The following example demonstrates several things. It shows how a static method is implemented on a class and that a class with a static member can be subclassed. Finally it shows how a static method can and cannot be called.</p>

<pre class="brush: js">
class Triple {
  static triple(n) {
    n = n || 1; //should not be a bitwise operation 
    return n * 3;
  }
}

class BiggerTriple extends Triple {
  static triple(n) {
    return super.triple(n) * super.triple(n);
  }
}

console.log(Triple.triple());        // 3
console.log(Triple.triple(6));       // 18
console.log(BiggerTriple.triple(3)); // 81
var tp = new Triple();
console.log(BiggerTriple.triple(3)); // 81 (not affected by parent's instantiation)
console.log(tp.triple());            // 'tp.triple is not a function'.</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('ES6', '#sec-class-definitions', 'Class definitions')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td>Initial definition.</td>
  </tr>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-class-definitions', 'Class definitions')}}</td>
   <td>{{Spec2('ESDraft')}}</td>
   <td>&nbsp;</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<p>{{CompatibilityTable}}</p>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatChrome(42.0)}}</td>
   <td>{{CompatGeckoDesktop(45)}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
   <th>Chrome for Android</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatGeckoMobile(45)}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatChrome(42.0)}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="See_also">See also</h2>

<ul>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Operators/class"><code>class</code> expression</a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Statements/class"><code>class</code> declaration</a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Classes">Classes</a></li>
</ul>