gsans

<!-- this is set to the DOM element -->
<a href="#" class="myclass another" id="1" onclick="alert(this.id + ' ' + this.className)">DOM element</a>

gsans

function Fn(a, b) { return a + b + this; };
// implicit this = 1
console.log(Fn.call(1, 2, 3)); //6
console.log(Fn.apply(1, [2, 3])); //6
//note: if null is passed this = window

gsans

//constructor function
function Person(id) {
 //new keyword implicit this = {};
 this.id = id;
 //new keyword implicit return this;
};
//this points to new object
var person = new Person(1);

gsans

// object scope
var scope = {
 number: 7,
 Fn: function() {
 return this.number; 
 }
};
// this points to scope (not window)
console.log(scope.Fn()); // 7

gsans

var number = 7;
console.log(this.number === window.number); // true
…
another = 8; // global variable
console.log(this.another === window.another); // true
…
//within a function this is set to window
function Fn() {
 return this;
};

gsans

//creation separated from initialisation
var order = {};
…
order.id = 1;
…
order.customer = {}; //ups I did it again
order.customer.id = 1;

gsans

//creation and initialisation together
var order = {
 id: 1,
 customer: { 
 id: 1
 }
};

gsans

//Using standard function definition
//note: convention is to use initial capital letter
function Order(id) {
 //new keyword implicit code: var this = {};
 this.id = id;
 //implicit: return this;
};
…
var order = new Order(1);

gsans

//Using an anonymous function reference
var Order = function(id) { 
 //new keyword implicit code: var this = {};
 this.id = id;
 //implicit: return this;
};
…
var order = new Order(1);

gsans

//Using a new object
var Order = function(id) { 
 //we ignore ‘this’ altogether… it’s evil right?
 var that = {};
 that.id = id;
 return that;
};
…
var order = new Order(1);