Arrays

• you do not have to declare a fixed size for an array when you create it
• if you do specify a size, the values are NULL until they are set

var myArray = new Array();
myArray[0] = "Alice";
myArray[1] = "Fred";
...

• if you supply more than one argument to Array(), the values are treated as data for the array

var myArray = new Array("Alice", "Fred", "Jean");
 
// or
 
var myArray = ["Alice", "Fred", "Jean"];

• use the .length property to determine the number of items, which is the same as the next available index since arrays are 0 based:

myArray[myArray.length] = "Steve";

• use join to create a string of all array items:

  var arrayAsString = myArray.join(","); // a comma is inserted between each item

• use split to create an array of items from a string:

  var restoredArray = myRegularString.split(",");

• split is more powerful, because regular expressions can be used as the separator parameter; the following creates an array of just the integer portions of values, looking for a period followed by two numerals and an optional comma:

  var amounts = "30.25,120.00,45.09,200.10";
  var amtArray = amounts.split(/\.\d{2},?/);