What's the difference between `f()` and `new f()`? [duplicate]

Answer 1

The new in your case isn't usefull. You only need to use the new keyword when the function uses the 'this' keyword.

function f(){
    this.a;
}
// new is required.
var x = new f();

function f(){
    return {
        a:1
    }
}
// new is not required.
var y = f();