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How to Create Random Numbers & Characters

This page shows you how to create a random sequence of numbers and/or text. The function which generates the random string can be called from any event handler - the example below uses a button.


Step 1

Add the following code to your head:

<script language="javascript" type="text/javascript">
function randomString() {
	var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
	var string_length = 8;
	var randomstring = '';
	for (var i=0; i<string_length; i++) {
		var rnum = Math.floor(Math.random() * chars.length);
		randomstring += chars.substring(rnum,rnum+1);
	document.randform.randomfield.value = randomstring;

Variables to set:

  1. chars - The random string will be created from these characters.
  2. string_length - The length of the random string.

Step 2

Use the following code for your text field and button:

<form name="randform">
<input type="button" value="Create Random String" onClick="randomString();">&nbsp;
<input type="text" name="randomfield" value="">