Mahdi_Nine Mahdi_Nine - 8 months ago 19
Javascript Question

How do I check for null values in JavaScript?

How can I check for null values in JavaScript? I wrote the code below but it didn't work.

if (pass == null || cpass == null || email == null || cemail == null || user == null) {

alert("fill all columns");
return false;


And how can I find errors in my JavaScript programs?


Javascript is very flexible with regards to checking for "null" values. I'm guessing you're actually looking for empty strings, in which case this simpler code will work:

if(!pass || !cpass || !email || !cemail || !user){

Which will check for empty strings (""), null, undefined, false and the numbers 0 and NaN