How to Setup a Randomising Function
By Arbitrary Constant2007-11-17
Displaying the random entity
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Once we have a randomising function, returning a random entity is straightforward: we simply call upon the script to
write the quote associated with the number generated by the random function:
document.write(quotes[rand(quotes.length)-1])
Here,
rand is the function as defined before, (quotes.length)-1 is the range of quotes we defined in the array and document.write
is the JavaScript command that returns the "value" created within the
parenthesis. It is then this entity that will be displayed on the
webpage.
Thus, the entire script looks a little like this:
quotes = new Array
(
"This is quote 1",
"This is quote 2",
"This is quote 3",
...
"This is the last quote"
);
rnd.today=new Date();
rnd.seed=rnd.today.getTime();
function rnd()
{
rnd.seed = (rnd.seed*9301+49297) % 233280;
return rnd.seed/(233280.0);
};
function rand(number)
{
return Math.ceil(rnd()*number);
};
document.write(quotes[rand(quotes.length)-1])
All that remains now is to decide where to include
the code for you html page. There are two main options: 1) within the
html page on which you want to utilise it or 2) as an external script
called upon by the html page when it loaded. In the first case, you
need to include the
script tag within the html header or body:
<script type="text/javascript">
insert script here
</script>
The first method should ideally be used for a script that is used only
in a particular circustance, whereas the external link is best employed
when a script is used on many changes and would therefore require much
more time if it were to be altered on each page it is used. That is the
method used on this website.
The second method is similar to that employed for
a style sheet and involves an external link to the script in the
following manner:
<script type="text/javascript" src="script.js">
</script>
Tutorial Pages:
» How to set up a randomising function
» Defining your entities
» Defining a randomising function
» Displaying the random entity
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