window.prompt help required

computerzworld

Hello,
I am suing window.prompt() to enter one text value from the user, storing it in javascript variable & sending it using ajax to php script in order to save it in database. I want to validate this input whether user have entered value or not. But I am unable to do so. Here is my javascript code.

var userInput = window.prompt('please enter value');

if(userInput!="" || userInput!=null)
{
        AJAX CODE FOR INSERTING VALUE IN DATABASE......
}

But this code doesn't works.. Please help me. Thanks in advance.

_uk_stuff

You could check that the userInput length is greater than 0 (zero). To do this you could replace the if statement conditions with:

if ( userInput.length > 0 )
{
AJAX CODE FOR INSERTING VALUE IN DATABASE......
}

Weedpacket

if(userInput!="" || userInput!=null)

This will always be true: an empty string is not null, null is not an empty string, and "fnord" is neither.
You meant to write "&&", not "||".

computerzworld

thanks for the reply.... The length attribute works fine but when I click on cancel button & trying to alert the response it gives as null. So, how can I compare null string in javascript? because in the browser error console it gives string is null error....

Weedpacket

Because null doesn't have a length attribute. You should look to see if userInput is null first, and only try looking at its attributes if it is not (i.e., if(userInput!=null && userInput.length>0)....).

It almost goes without saying that if it is null it won't have any attributes for you to look at.