Question

Below is a code snippet, where we retrieve a form value.
Before further processing check if the value is not null..

var val = document.FileList.hiddenInfo.value;
alert("val is " + val);  // this prints null which is as expected
if (val != null)
{
   alert("value is "+val.length); // this returns 4
}
else
{
   alert("value* is null");
}

Any ideas why it happens so.. ??

Answer 1

It’s because val is not null, but contains 'null' as a string.

Try to check with ‘null’

if ('null' != val)

For an explanation of when and why this works, see the details below.