3.1 Creating a Simple Array
NN 3, IE 4
want to create a simple array of data.
populate an array. The long way is to use the
Array object constructor. If you specify
no parameters for the constructor, you create an empty array, which
you may then populate with data entry by entry:
var myArray = new Array( );
myArray = "Alice";
myArray = "Fred";
You do not have to declare a fixed size for an array when you create
it, but you may do so if you wish, by passing a single integer value
as a parameter to the constructor method:
var myArray = new Array(12);
This creates an array of 12 entries whose values are
If you supply more than one comma-delimited parameter to the
constructor method, the arguments are treated as data for the array
entries. Thus, the following statement:
var myArray = new Array("Alice", "Fred", "Jean");
creates a three-item array, each item containing a string value.
A shortcut approach to the same action lets you use
to symbolize the array constructor:
var myArray = ["Alice", "Fred", "Jean"];
You can use the shortcut syntax in IE 4 or later and NN 4 or later.
After you create an array (through any of the syntaxes just shown),
you can add to it by assigning a value to the array with the next
numeric index in sequence. If your script doesn't
know how large an array is when it needs to add to it, you can use
the length property of the array to help out.
Because the length integer is always one larger than the highest
zero-based index value of the array, the length
value can act as the index for the next item:
myArray[myArray.length] = "Steve";
In fact, you can use this construction to populate any existing array
object, including an empty one. This is particularly helpful if you
are populating a large array and need to change values in the source
code from time to time. Rather than trying to juggle fixed index
numbers in a long series of assignment statements, use the
length property, and order the assignment
statements so that all items are in the desired array order. The
indexes will take care of themselves when the statements run, even if
you change the order in the source code tomorrow.
3.1.4 See Also
Recipe 3.2 for creating a more complex array; Recipe 3.8 for a
discussion about creating an array of objects; Recipe 3.3 for
converting an array's entries to a string value.