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Validating empty input with jQuery

I post comments via $ .ajax. However, I want to check that some content has been entered in the input field. At the moment I am using this:

if ($("#comments").val().length != 0){

However, this only works if the user leaves the input space, if you leave a space or return, then it will pass. How can I improve this if?

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4 answers

Delete the space before checking for empty:

 if ($("#comments").val().replace(/^\s+|\s+$/g, "").length != 0){
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you can go for the trim function ... google give us good links. btw ... jQuery has trim-function

eg.

 var trimmedValue = jQuery.trim($('#comments').val()); if (trimmedValue.length > 0) { // TODO }
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In javascript

 //Following all return true "" == false " " == false " " == false " " == false //Not related to question but interesting //Following all (also) return true !" " == false !" " == false !" " == false //Except !"" == false //returns false

(verified using the Firebug console and the Chromium Developer Tools console).

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I know this is an incredibly late answer, but I use this ...

 var self = $(this).val(); if (!self || self[0] == ' '){ //////do something }

and it works well! hope someone else can benefit from it!

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