Random Number With JavaScript

When you need to generate a random number with JavaScript, the RandomNumber() function can be used.

RandomNumber() expects two values, the minimum number and the maximum number. It returns a random integer within that range. If the minimum is specified as 2 and the maximum as 5, the random number returned with be 2, 3, 4, or 5.

The minimum and maximum numbers may be positive or negative numbers. if the minimum is -1 and the maximum is 1, the returned random number will be -1, 0, or 1.

The minimum and maximum numbers may be may be integers or decimal numbers. If the minimum is 1.5 and the maximum is 3.5, the returned random number will be 2 or 3.

If the minimum number is larger than the maximum number, RandomNumber() will swap the values before randomly selecting a number within the range.

Here is the source code of the RandomNumber() function. Code is included for testing the function.

<script type="text/javascript">
// Copyright 2010 Bontrager Connection, LLC
// Bontrager Connection, LLC grants you a royalty free license to use or modify this software provided this notice appears on all copies. This software is provided "AS IS," without a warranty of any kind.

// The random number function
function RandomNumber(min,max) {
if(max<min) {
   var i=max;
   max=min;
   min=i;
   }
return Math.round(Math.random()*(max-min)+min);
}

// Testing the function: 100 throws of a pair of dice.
for(var i=1; i<=100; i++) {
   var die1 = RandomNumber(1,6);
   var die2 = RandomNumber(1,6);
   var pair = (die1==die2) ? " <u>pair</u>" : "";
   document.write("("+die1+","+die2+") = <b>"+(die1+die2)+"</b>"+pair+"<br>");
   }

</script>

Copy the above and paste it into the source code of a web page anywhere in the BODY area that JavaScript can run. When the page is loaded into a JavaScript-enabled browser, the testing code will print 100 representations of pseudo-random dice throws.

Below is a live representation of 100 throws of a pair of dice generated with RandomNumber(). Click the [100 more throws] button to generate another 100 throws.

The RandomNumber() function can be used to get a random positive or negative number within a specified minimum and maximum range.

Will Bontrager