Arrays and Objects

AO.js

//Bad way to declare objects and arrays
var person = new Object(),
    keys = new Array();

//A better way is to use object literals
var person = {},
    keys = [];

//Example
var person = {
    firstname : "Paul",
    lastName : "Allies"
}
    
var keys = ["123", "345"];
keys[5] = "444";
Y.log("The length of keys: " + keys.length);

//if we use the for loop we may pull out undefined values
for(var i= 0; i < keys.length; i++)
{
    Y.log(keys[i]);
}

//always use the for in
for(name in keys)
{
    Y.log(keys[name]);
}