The script defines a variable called "test" with the value "tester". It then finds the input element with id "test" and sets its value to the variable. Elsewhere on the page, a form is defined with an input called "test" that will be set to "tester" and submitted when the submit button is clicked.

1. <script type="text/javascript" charset="utf-8">
var test = "tester";
// find the 'test' input element and set its value to the above variable
document.getElementByID("test").value = test;
</script>
... elsewhere on your page ...
<form method="get" action="blah.php">
<input id="test" name="test" visibility="hidden"></input>
<input type="submit" value="Click me!"></input>
</form>