jquery if text input does not equal blank

Question

I am trying to work out how to do something if a certain text box is not empty (i.e. contain something, could be anything)

This is my code (that doesnt seem to work)

if ( !($('#edit-sPostalCode').attr('val','')) ) {
    stuff here
}

What have I missed?

There is no HTML element which has a val attribute. I think you mean the jQuery method .val(). — Felix Kling
– Felix Kling, Commented Nov 11, 2011 at 15:05

El Ronnoco · Accepted Answer · 2011-11-11 15:41:47Z

11

if ( $('#edit-sPostalCode').val() != '' ) {
    stuff here
}

$('#edit-sPostalCode').attr('val','') will actually create an attribute of the input box with a value of '' and will then return a jQuery object.

Saying !($('#edit-sPostalCode').attr('val','')) will then negate that jQuery object. As an instance of an object is truthy in JS the result of this expression will always be false.

edited Nov 11, 2011 at 15:41

answered Nov 11, 2011 at 15:05

El Ronnoco

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1 Comment

Felix Kling Over a year ago

It would not set the value, it will add a new attribute with name val. But apart from that, you are right.

Blazemonger · Accepted Answer · 2011-11-11 15:06:13Z

2

Are you aware of the .val method?

if ( $('#edit-sPostalCode').val() !== '' ) {

Although you ought to $.trim the value if you consider whitespace as being equivalent to nothing at all:

if ( $.trim( $('#edit-sPostalCode').val() ) !== '' ) {

answered Nov 11, 2011 at 15:06

Blazemonger

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4 Comments

Nicholas Murray Over a year ago

is !== a javascript operator? I know === is

Nicholas Murray Over a year ago

Just googled it there - is this the best for this comparison?

Blazemonger Over a year ago

@NicholasMurray It might not matter, but it's better to be safe. For instance, in JavaScript, false=='0' is true. false=='' is also true, although ''=='0' is false.

Nicholas Murray Over a year ago

@FelixKling - cool I've changed my answer to use === instead.

Nicholas Murray · Accepted Answer · 2011-11-11 15:35:13Z

0

if ( !($('#edit-sPostalCode').val() === '') ) {
    stuff here
}

edited Nov 11, 2011 at 15:35

answered Nov 11, 2011 at 15:04

Nicholas Murray

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