How to assign null value to Hidden variable in javascript?

Question

I have a hidden input variable called str.

I am assigning "abc" value to it.

Then I try to assign null value or let's say null reference to it. But I couldn't.

Edit

part of code.

Hidden Field...

<input id="str" name="str" type="hidden" value="" />

I also use jQuery.

if ($(str).val() == "abc") {
     $("#str").val(null);
             }

Do you have some code you can paste into the question here?

C. K. Young
– C. K. Young

2009-05-12 13:30:29 +00:00
Commented May 12, 2009 at 13:30 — C. K. Young
– C. K. Young, Commented May 12, 2009 at 13:30
Can we see some code, please?

Marc W
– Marc W

2009-05-12 13:30:33 +00:00
Commented May 12, 2009 at 13:30 — Marc W
– Marc W, Commented May 12, 2009 at 13:30

Peter Boughton · Accepted Answer · 2009-05-12 13:39:39Z

12

I'm not sure nulling the value is meaningful - you should either blank the value, or delete the whole field (not just the value).

Based on the example code you provided...

For example:

$("#str").val('')

or

$("#str").remove()

Another option, if you may need to toggle the field on or off (so rather than deleting & re-creating) would be disabling the field - disabled fields don't get submitted with the form.

$("#str").attr('disabled','disabled')
and
$("#str").removeAttr('disabled')

edited May 12, 2009 at 13:39

answered May 12, 2009 at 13:33

Peter Boughton

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1 Comment

KyleFarris Over a year ago

You can't assign NULL to an element's value--it is HTML. HTML can't differentiate from the keyword NULL and the string 'null' if its placed in the actual tag and, therefore, neither can jQuery in this context. Peter is right about his answer(s). If you want to return an empty string result when querying that element, use his first example. If you want to return 'undefined' (not a string), use his second example.

tvanfosson · Accepted Answer · 2009-05-12 13:37:57Z

1

Assign the empty string to it. It will be treated the same way on the server side.

 var inp = document.getElementById('str');
 inp.value = '';  // actually inp.value = null will work here

Or using jQuery

 if ($(str).val() == "abc")
 {
     $("#str").val('');
 }

edited May 12, 2009 at 13:37

answered May 12, 2009 at 13:31

tvanfosson

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