mozilla
Your Search Results

    Function.name

    This is an experimental technology, part of the ECMAScript 6 (Harmony) proposal.
    Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future version of browsers as the spec changes.

    Summary

    The function.name property returns the name of the function.

    Property attributes of Function.name
    Writable no
    Enumerable no
    Configurable yes

    Description

    The name property returns the name of a function, or an empty string for anonymous functions:

    function doSomething() {}
    
    console.log(doSomething.name); // logs "doSomething"
    

    Functions created with the syntax new Function(...) or just Function(...) have their name property set to an empty string. In the following examples anonymous functions are created, so name returns an empty string:

    var f = function() {};
    var object = {
      someMethod: function() {}
    };
    
    console.log(f.name == ''); // true
    console.log(object.someMethod.name == ''); // also true
    

    You can define a function with a name in a function expression:

    var object = {
      someMethod: function object_someMethod() {}
    };
    console.log(object.someMethod.name); // logs "object_someMethod"
    
    try { object_someMethod } catch(e) { console.log(e); }
    // ReferenceError: object_someMethod is not defined
    

    You cannot change the name of a function, this property is read-only:

    var object = {
      // anonymous
      someMethod: function() {}
    };
    
    object.someMethod.name = 'someMethod';
    console.log(object.someMethod.name); // empty string, someMethod is anonymous
    

    Examples

    You can use obj.constructor.name to check the "class" of an object:

    function a() {}
    
    var b = new a();
    
    console.log(b.constructor.name); // logs "a"
    

    Specifications

    Specification Status Comment
    ECMAScript 6 (ECMA-262)
    The definition of 'name' in that specification.
    Release Candidate Initial definition.

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support 33 (Yes) Not supported (Yes) (Yes)
    Configurable: true 43 38 (38) ? ? ?
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support (Yes) (Yes) (Yes) Not supported (Yes) (Yes)
    Configurable: true ? ? 38.0 (38) ? ? ?

    Document Tags and Contributors

    Last updated by: fscholz,