Javascript

Related applications

Search a word:

Javascript arrays

Array:

1. Definition


We declare an array of n elements as follows:
var ARRAY = new Array();
ARRAY[0] = value0;
...
ARRAY[n-1] = valueN;

The value could be number or string.

Example:
We declare an array as follows:
var rare_gases = new Array();
rare_gases[0] = "helium";
rare_gases[1] = "neon";
rare_gases[2] = "argon";
rare_gases[3] = "krypton";
rare_gases[4] = "xenon";
rare_gases[5] = "radon";

We use the for...in statement to loop through the 
elements of an array.

Syntax:

for (variable in array)
{
some code to be executed ... 
}

2. Example:


<body>
<script type="text/javascript">
var atom;
var rare_gases = new Array();
rare_gases[0] = "helium";
rare_gases[1] = "neon";
rare_gases[2] = "argon";
rare_gases[3] = "krypton";
rare_gases[4] = "xenon";
rare_gases[5] = "radon";

for (atom in rare_gases)
{
document.write("- " + rare_gases[atom] + "<br />");
}
</script>
</body>

Will output:

- helium
- neon
- argon
- krypton
- xenon
- radon

3. Sorting an array:


Here is an example:
	<head>
	<script type="text/javascript">

	function initialize(the_array) {
	for (var i=0; i<the_array.length; i++)
	the_array[i] = Math.floor(Math.random()*100)
	}

	function display(the_array) {
	document.write('(');
	for (var i=0; i<the_array.length; i++) {
	if (i != 0)
	document.write(', ');
	document.write(the_array[i]);
	}
	document.writeln(')<br>');
	}

	function sorting(the_array) {
	var minpos;
	var intermed;
	for (var j=0; j<the_array.length-1; j++) {
	minpos=j;
	for (var i=j+1; i<the_array.length; i++) {
	if (the_array[i] < the_array[minpos])
	minpos = i;
	}
	intermed = the_array[j];
	the_array[j] = the_array[minpos];
	the_array[minpos] = intermed;
	}
	}
	// -->
	</script>
	</head>
	
	<body>
	<script type="text/javascript">
	//create an instance object: an empty arrat
	var the_array = new Array(20);
	//then apply the metods defined in the head section:
	initialize(the_array);
	document.writeln('<H4>This an array of random numbers</H4>');
	display(the_array);
	sorting(the_array);
	document.writeln('<BR> <H4>The same array after swapping</H4>');
	display(the_array);
	</script>
	</body>

The output is:

3. Creating an array:


An array can be created using two methods:

1. The JavaScript Array object:
var atom = new Array();
atom is an array.
We can also write:
var atom = new Array(N)
That is the array atom will have N elements.

We fill in the array as follows:
atom [0] = 'Helium';
atom [1] = 'Neon';
atom [2] = 'Argon';

or directly:
atom = new Array("Helium", "Neon","Argon");

2. Constructing an array manually using a makeArray() function.

function makeArray() {
    for (i = 0; i var atom = new makeArray("Helium", "Neon","Argon");

Example:
 
deck = new makeArray(13);
for (i=0; i<13; i++) {
deck[i] = i;
}

Web

ScientificSentence