checking textbox field

in my website ther is a textbox for entering year..

i have given code for displaying an alert message if the textbox is left empty..

   1. function validate() {
   2. if(document.form.year.value=="")
   3. {
   4. alert ('Please enter year');
   5. return false;
   6. }}

PHP:

it is working , but i want to do is..

it should display an alert message if the length of the numbers is less than 4 or greater than 4

how can i do that??

please give me a solution...
thanks......

 

Your asking for it to display a separate alert message is the length is greater or less than 4?

 

yes..
i want to display a seperate alert message if the length is greater or less than 4..

 

Hi, this function should solve it for you.

Cheers,
Rich..

function validate()
{
if(document.form.year.value=="")
{
alert ('Please enter year');
return false;
}

else if(document.form.year.value.length > 4)
{
alert ('The year must be in the format "YYYY"');
return false;
}

else if(document.form.year.value.length < 4)
{
alert ('The year must be in the format "YYYY"');
return false;
}

}