Selecting empty text input using jQuery

You could also do it by defining your own selector:

$.extend($.expr[':'],{
    textboxEmpty: function(el){
        return $(el).val() === "";
    }
});

And then access them like this:

alert($(':text:textboxEmpty').length); //alerts the number of text boxes in your selection

As mentioned in the top ranked post, the following works with the Sizzle engine.

$('input:text[value=""]');

In the comments, it was noted that removing the :text portion of the selector causes the selector to fail. I believe what's happening is that Sizzle actually relies on the browser's built in selector engine when possible. When :text is added to the selector, it becomes a non-standard CSS selector and thereby must needs be handled by Sizzle itself. This means that Sizzle checks the current value of the INPUT, instead of the "value" attribute specified in the source HTML.

So it's a clever way to check for empty text fields, but I think it relies on a behavior specific to the Sizzle engine (that of using the current value of the INPUT instead of the attribute defined in the source code). While Sizzle might return elements that match this selector, document.querySelectorAll will only return elements that have value="" in the HTML. Caveat emptor.

$(":text[value='']").doStuff();

?

By the way, your call of:

$('input[id=cmdSubmit]')...

can be greatly simplified and speeded up with:

$('#cmdSubmit')...

Another way

$('input:text').filter(function() { return $(this).val() == ""; });

or

$('input:text').filter(function() { return this.value == ""; });

or

// WARNING: if input element does not have the "value" attribute or this attribute was removed from DOM then such selector WILL NOT WORK! 
// For example input with type="file" and file does not selected.
// It's prefer to use "filter()" method.
// Thanks to @AaronLS
$('input:text[value=""]');

Working Demo

code from the demo

jQuery

 $(function() {

  $('#button').click(function() {

    var emptyTextBoxes = $('input:text').filter(function() { return this.value == ""; });
    var string = "The blank textbox ids are - \n";

    emptyTextBoxes.each(function() {
      string += "\n" + this.id;
    });
    alert(string);
  });

});