Functions this Solution

functions_this_solution.js

var person = {
    first_name: "Robert",
    last_name: "Barker",
    nick_name: "Bob",
    full_name: undefined,
    name_helper: function (short) {
        var that = this; // the important part
        var shorter_name = function () {
            // this to that
            that.full_name = that.nick_name + " " + that.last_name;
        };
        
        var bigger_name  = function () {
            // this to that
            that.full_name = that.first_name + " " + that.last_name;
        };
        
        if (short) {
            shorter_name();
        } else {
            bigger_name();
        }
    }
};
    
alert(person.full_name); // undefined
person.name_helper(true);
alert(person.full_name); // Bob Barker