Question

For example, I have the below constructor:

function MyType(){

    this.someProp = 'someText';

};

I create a new instance:

var myVar = new MyType();

Now I want to check the type of this object…

console.log(typeof(myVar));    //object
console.log(myVar.toString()); //[object Object]

Is there any way for typeof or the default toString method to return MyType, instead of just object.

• The above has been tested in Chrome console.

• JSFiddle: http://jsfiddle.net/keqHN/

Answer 1

No, you cannot override the behaviour of typeof. It’s defined in the spec and there are a set number of possible return values. It uses the “type” of the operand, which can only be one of null, undefined, string, boolean, number and object.

However, instanceof should work:

console.log(myVar instanceof MyType); // true

Side note… typeof is an operator, not a function, so you don’t need the parentheses around it.