var sayAge = function(){
console.log(this.age)
}
var me = {
age:25
}
/* When the 'this' keyword is used in the sayAge() function, there is nothing to the left of sayAge. As a result, 'this' defaults to the window object. sayAge, because it uses the `this` keyword, needs to be ran in the right context. */
sayAge(); // This returns `undefined`
// We can explicitly set the context using call(), apply(), or bind()
sayAge.call(me)