Getting an empty JQuery object

Question

In the following code I set up a change handler on a select box to show and hide some follow up questions based on the value of the selection.

Further, for some values of the selection there is an extra message that is displayed.

In order to check to see if I need to hide the extra message, I keep a variable called Previous. Upon execution of the handler I check to see if Previous is null or if the size is 0.

It would be nice to initialize Previous to an empty JQuery object so as not to have to do the extra check for null.

Doing a $() returns an object with the size of 1.

Is there a way to create an empty Jquery object?

//Init function.
$(function(){
//Hold the previously selected object for the account type selection.

var Previous = null;  //Here is where I would like to initialize.
                      //something like Previous = $();


$("SELECT[name='AccountType']").change(
    function () {
        //Hide Previous message if there was one.
        if(Previous == null || Previous.size() > 0){ 
            Previous.hide();
        }

        //Show the message if found and save it as previous.
        Previous = $("#"+this.value+"_Msg").show();

        //Get fisrt question
        var FirstQuestion = $(".FirstQuestion");
        if(this.value === ''){
            FirstQuestion.hide();
        }else{
            //Manually show FirstQuestion.
            FirstQuestion.show();
        }
    });
}

In the worst case I could do something like this:

    var Previous = { size : function () { return 0; } };

but that seems like overkill.

Magnar · Accepted Answer · 2011-06-23 05:44:31Z

241

This creates an empty jQuery-object:

$([])

Update: In newer versions of jQuery (1.4+), you can use:

$()

edited Jun 23, 2011 at 5:44

answered May 22, 2009 at 11:03

Magnar

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3 Comments

cregox Over a year ago

thanks. So which one is better to keep the compatibility with previous and further versions? - Anyway, I still can't figure out why neither worked in my case. Maybe I should open a question about it, but I solved it by using PHP instead of jQuery so I can't really dig more into it right now.

zloctb Over a year ago

fine test: $().add($("div")).css('color','red');

Mayur Over a year ago

How to make that var Values = {} this empty after use . I filled this object in the success of ajax call. But after use i want to make it empty so when next request came it follows same patter.

Marco Kerwitz · Accepted Answer · 2015-03-14 08:51:15Z

25

$();

Returning an Empty Set

As of jQuery 1.4, calling the jQuery() method with no arguments returns an empty jQuery set (with a .length property of 0). In previous versions of jQuery, this would return a set containing the document node.

Source: api.jquery.com

edited Mar 14, 2015 at 8:51

Marco Kerwitz

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answered Sep 13, 2010 at 16:46

Tom Hubbard

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2 Comments

studgeek Over a year ago

Providing the link (api.jquery.com/jQuery/#jQuery1) to back your statement up would probably get you more ups :).

ksadowski Over a year ago

Upvoted for the included source. Always great to have all the context available. A more direct link to the related paragraph would be: api.jquery.com/jQuery/#returning-empty-set

cletus · Accepted Answer · 2009-05-22 11:04:43Z

My advice is don't do it that way. There are a lot easier ways of doing this. Consider:

<select id="select" name="select">
  <option value="msg_1">Message 1</option>
  <option value="msg_2">Message 1</option>
  <option value="msg_3">Message 1</option>
</select>

<div class="msg_1 msg_3">
  ...
</div>

<div class="msg_1">
  ...
</div>

<div class="msg_2">
  ...
</div>

$(function() {
  $("#select").change(function() {
    var val = $(this).val();
    $("div." + val").show();
    $("div:not(." + val + ")").hide();
  });
});

Much easier. Basically give classes to indicate what to show and hide and then there is no tracking required. An alternative is:

$(function() {
  $("#select").change(function() {
    var val = $(this).val();
    $("div").each(function() {
      if ($(this).hasClass(val)) {
        $(this).show();
      } else {
        $(this).hide();
      }
    });
  });
});

Bane Neba · Accepted Answer · 2020-05-03 07:53:47Z

0

try this

 var new = $([]);

I ain't a good programmer but it gives u empty object :))

edited May 3, 2020 at 7:53

answered Feb 19, 2020 at 4:51

Bane Neba

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1 Comment

isherwood Over a year ago

You're getting downvotes because you've repeated an existing (and very old) answer. That doesn't add any value to the community.

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