Check if inputs are empty using jQuery

Question

I have a form that I would like all fields to be filled in. If a field is clicked into and then not filled out, I would like to display a red background.

Here is my code:

$('#apply-form input').blur(function () {
  if ($('input:text').is(":empty")) {
    $(this).parents('p').addClass('warning');
  }
});

It applies the warning class regardless of the field being filled in or not.

What am I doing wrong?

Answer 1

$('#apply-form input').blur(function()
{
    if( !$(this).val() ) {
          $(this).parents('p').addClass('warning');
    }
});

And you don't necessarily need .length or see if it's >0 since an empty string evaluates to false anyway but if you'd like to for readability purposes:

$('#apply-form input').blur(function()
{
    if( $(this).val().length === 0 ) {
        $(this).parents('p').addClass('warning');
    }
});

If you're sure it will always operate on a textfield element then you can just use this.value.

$('#apply-form input').blur(function()
{
      if( !this.value ) {
            $(this).parents('p').addClass('warning');
      }
});

Also you should take note that $('input:text') grabs multiple elements, specify a context or use the this keyword if you just want a reference to a lone element (provided there's one textfield in the context's descendants/children).

Answer 2

Everybody has the right idea, but I like to be a little more explicit and trim the values.

$('#apply-form input').blur(function() {
     if(!$.trim(this.value).length) { // zero-length string AFTER a trim
            $(this).parents('p').addClass('warning');
     }
});

if you dont use .length , then an entry of '0' can get flagged as bad, and an entry of 5 spaces could get marked as ok without the $.trim . Best of Luck.

Answer 3

Doing it on blur is too limited. It assumes there was focus on the form field, so I prefer to do it on submit, and map through the input. After years of dealing with fancy blur, focus, etc. tricks, keeping things simpler will yield more usability where it counts.

$('#signupform').submit(function() {
    var errors = 0;
    $("#signupform :input").map(function(){
         if( !$(this).val() ) {
              $(this).parents('td').addClass('warning');
              errors++;
        } else if ($(this).val()) {
              $(this).parents('td').removeClass('warning');
        }   
    });
    if(errors > 0){
        $('#errorwarn').text("All fields are required");
        return false;
    }
    // do the ajax..    
});

Answer 4

if ($('input:text').val().length == 0) {
      $(this).parents('p').addClass('warning');
}

Answer 5

you can use also..

$('#apply-form input').blur(function()
{
    if( $(this).val() == '' ) {
          $(this).parents('p').addClass('warning');
    }
});

if you have doubt about spaces,then try..

$('#apply-form input').blur(function()
{
    if( $(this).val().trim() == '' ) {
          $(this).parents('p').addClass('warning');
    }
});

Answer 6

how come nobody mentioned

$(this).filter('[value=]').addClass('warning');

seems more jquery-like to me

Answer 7

The keyup event will detect if the user has cleared the box as well (i.e. backspace raises the event but backspace does not raise the keypress event in IE)

    $("#inputname").keyup(function() {

if (!this.value) {
    alert('The box is empty');
}});

Answer 8

Consider using the jQuery validation plugin instead. It may be slightly overkill for simple required fields, but it mature enough that it handles edge cases you haven't even thought of yet (nor would any of us until we ran into them).

You can tag the required fields with a class of "required", run a $('form').validate() in $(document).ready() and that's all it takes.

It's even hosted on the Microsoft CDN too, for speedy delivery: http://www.asp.net/ajaxlibrary/CDN.ashx

Answer 9

The :empty pseudo-selector is used to see if an element contains no childs, you should check the value :

$('#apply-form input').blur(function() {
     if(!this.value) { // zero-length string
            $(this).parents('p').addClass('warning');
     }
});

Answer 10

There is one other thing you might want to think about, Currently it can only add the warning class if it is empty, how about removing the class again when the form is not empty anymore.

like this:

$('#apply-form input').blur(function()
{
    if( !$(this).val() ) {
          $(this).parents('p').addClass('warning');
    } else if ($(this).val()) {
          $(this).parents('p').removeClass('warning');
    }
});

Answer 11

function checkForm() {
  return $('input[type=text]').filter(function () {
    return $(this).val().length === 0;
  }).length;
}

Answer 12

Here is an example using keyup for the selected input. It uses a trim as well to make sure that a sequence of just white space characters doesn't trigger a truthy response. This is an example that can be used to begin a search box or something related to that type of functionality.

YourObjNameSpace.yourJqueryInputElement.keyup(function (e){
   if($.trim($(this).val())){
       // trimmed value is truthy meaning real characters are entered
    }else{
       // trimmed value is falsey meaning empty input excluding just whitespace characters
    }
}

Answer 13

$(function() {
  var fields = $('#search_form').serializeArray();
  is_blank = true;
  for (var i = 0; i < fields.length; i++) {
    // excluded fields
    if ((fields[i].name != "locale") && (fields[i].name != "utf8")) {
      if (fields[i].value) {
        is_blank = false;
      }
    }
  }
  if (is_blank) {
    $('#filters-button').append(': OFF');
  }
  else {
    $('#filters-button').append(': ON');
  }
});

Check if all fields are empty and append ON or OFF on Filter_button

Answer 14

You can try something like this:

$('#apply-form input[value!=""]').blur(function() {
    $(this).parents('p').addClass('warning');
});

It will apply .blur() event only to the inputs with empty values.

Answer 15

Please use this code for input text

$('#search').on("input",function (e) {

});

Answer 16

<script type="text/javascript">
$('input:text, input:password, textarea').blur(function()
    {
          var check = $(this).val();
          if(check == '')
          {
                $(this).parent().addClass('ym-error');
          }
          else
          {
                $(this).parent().removeClass('ym-error');  
          }
    });
 </script>// :)

Answer 17

With HTML 5 we can use a new feature "required" the just add it to the tag which you want to be required like:

<input type='text' required>

Answer 18

Great collection of answers, would like to add that you can also do this using the :placeholder-shown CSS selector. A little cleaner to use IMO, especially if you're already using jQ and have placeholders on your inputs.

if ($('input#cust-descrip').is(':placeholder-shown')) {
  console.log('Empty');
}

$('input#cust-descrip').on('blur', '', function(ev) {
  if (!$('input#cust-descrip').is(':placeholder-shown')) {
    console.log('Has Text!');
  }
  else {
    console.log('Empty!');
  }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<input type="text" class="form-control" id="cust-descrip" autocomplete="off" placeholder="Description">

You can also make use of the :valid and :invalid selectors if you have inputs that are required. You can use these selectors if you are using the required attribute on an input.

Answer 19

A clean CSS-only solution this would be:

input[type="radio"]:read-only {
        pointer-events: none;
}