// creating a reusable helper
function foo(something){
    console.log( this.a, something );
    return this.a + something;
}

//simple 'bind' helper
function bind(fn, obj){
    return function() {
        return fn.apply( obj, arguments );
    };
}

var obj = {
    a: 2
};

var bar = bind( foo, obj );
var b = bar( 3 );
console.log( b );