How to get a JavaScript object's class?

Question

I created a JavaScript object, but how I can determine the class of that object?

I want something similar to Java's .getClass() method.

Answer 1

There's no exact counterpart to Java's getClass() in JavaScript. Mostly that's due to JavaScript being a prototype-based language, as opposed to Java being a class-based one.

Depending on what you need getClass() for, there are several options in JavaScript:

• typeof
• instanceof
• obj.constructor
• func.prototype, proto.isPrototypeOf

A few examples:

function Foo() {} var foo = new Foo();  typeof Foo;             // == "function" typeof foo;             // == "object"  foo instanceof Foo;     // == true foo.constructor.name;   // == "Foo" Foo.name                // == "Foo"      Foo.prototype.isPrototypeOf(foo);   // == true  Foo.prototype.bar = function (x) {return x+x;}; foo.bar(21);            // == 42 

Note: if you are compiling your code with Uglify it will change non-global class names. To prevent this, Uglify has a --mangle param that you can set to false is using gulp or grunt.