jQuery check if <input> exists and has a value

Question

I have the following example:

Is there a way to check if this element exists and ha

Answer 1

if($('#user_inp').length > 0 && $('#user_inp').val() != '')
{

    $('#user_inp').css({"font-size":"18px"});
    $('#user_line').css({"background-color":"#4cae4c","transition":"0.5s","height":"2px"});
    $('#username').css({"color":"#4cae4c","transition":"0.5s","font-size":"18px"});

}

Answer 2

I would do something like this: $('input[value]').something . This finds all inputs that have value and operates something onto them.

Answer 3

Just for the heck of it, I tracked this down in the jQuery code. The .val() function currently starts at line 165 of attributes.js. Here's the relevant section, with my annotations:

val: function( value ) {
    var hooks, ret, isFunction,
        elem = this[0];

        /// NO ARGUMENTS, BECAUSE NOT SETTING VALUE
    if ( !arguments.length ) {

        /// IF NOT DEFINED, THIS BLOCK IS NOT ENTERED. HENCE 'UNDEFINED'
        if ( elem ) {
            hooks = jQuery.valHooks[ elem.type ] || jQuery.valHooks[ elem.nodeName.toLowerCase() ];

            if ( hooks && "get" in hooks && (ret = hooks.get( elem, "value" )) !== undefined ) {
                return ret;
            }

            ret = elem.value;

            /// IF IS DEFINED, JQUERY WILL CHECK TYPE AND RETURN APPROPRIATE 'EMPTY' VALUE
            return typeof ret === "string" ?
                // handle most common string cases
                ret.replace(rreturn, "") :
                // handle cases where value is null/undef or number
                ret == null ? "" : ret;
        }

        return;
    }

So, you'll either get undefined or "" or null -- all of which evaluate as false in if statements.

Answer 4

You can create your own custom selector :hasValue and then use that to find, filter, or test any other jQuery elements.

jQuery.expr[':'].hasValue = function(el,index,match) {
  return el.value != "";
};

Then you can find elements like this:

var data = $("form input:hasValue").serialize();

Or test the current element with .is()

var elHasValue = $("#name").is(":hasValue");

jQuery.expr[':'].hasValue = function(el) {
  return el.value != "";
};


var data = $("form input:hasValue").serialize();
console.log(data)


var elHasValue = $("[name='LastName']").is(":hasValue");
console.log(elHasValue)

label { display: block; margin-top:10px; }

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<form>
  <label>
    First Name:
    <input type="text" name="FirstName" value="Frida" />
  </label>

  <label>
    Last Name:
    <input type="text" name="LastName" />
  </label>
</form>

Further Reading:

• Make jQuery :contains Case-Insensitive
• Make Your Own Custom jQuery Selector
• Exploring jQuery Selectors, Part 3

Answer 5

You could do:

if($('.input1').length && $('.input1').val().length)

length evaluates to false in a condition, when the value is 0.

Answer 6

The input won't have a value if it doesn't exist. Try this...

if($('.input1').val())