Constructor for callable object in JavaScript [duplicate]

Answer 1

I'm not sure if you're aware that your object will only be an instance of CallablePoint if you use the new keyword. By naming it "callable", you make me think you don't want to use new. Anyway, there is a way to force an instance to be returned (thanks for the tip, Resig):

function CallablePoint(x, y) {
    if (this instanceof CallablePoint) {
        // Your "constructor" code goes here.
        // And don't return from here.
    } else {
        return new CallablePoint(x, y);
    }
}

This will return an instance of CallablePoint regardless of how it was called:

var obj1 = CallablePoint(1,2);
console.log(obj1 instanceof CallablePoint); // true

var obj2 = new CallablePoint(1,2);
console.log(obj2 instanceof CallablePoint); // true