Javascript variable

As any other language, javascript is also has variables. Javascript is case sensitive, so the variable name is case sensitive too. So y variable is different with Y. Javascript variable name must begin with letter or underscore.

This is how you declare javascript variable:
Local Variable:
Has to be declare inside a function. Example:
<script type="text/javascript">
function print_hello()
{
var somewordempty;
document.write("empty " + somewordempty + "<br/>");
somewordempty="assign value to empty";
document.write(somewordempty + "<br/>");
var somewordassign ="assigned variable";
document.write(somewordassign + "<br/>");
}
print_hello();
</script>
Global Variable:
Has to be declare outside functions. I hope this example can make you understand. Example:
<script type="text/javascript">
var globalvar=" <br/>should be global";
document.write(globalvar);
function print_hello()
{
var globalvar="<br/>should be local, because although it have the same name but it declares under a function";
document.write(globalvar);
}
print_hello();
document.write(globalvar + " because it outside the function");
</script>
Let's try to call it again and you will get the same value as above. Because global variable is destroy when we close this page.
<script type="text/javascript">
document.write(globalvar);
</script>