foo.js

function FooObj(){
    this.location = "http://www.google.com"
    
    this.setLocation= function (location){
        this.location = location;
    }
}

var foo = new FooObj();
foo.setLocation("http://www.google.com/");
console.log(foo.location)

//what happens here?
var foos_setLocation = foo.setLocation
foos_setLocation("http://www.google.com/")