jQuery How to control, does an element exist in document?

Question

I want to control does an element exist in document with its ID, when page is loading. I tried code which is below, but i failed.

   if($(':not(#<%=TextBox1.ClientID %>)')){
     alert("Object is null")else{alert("Object is exist")}}

Thansk for your helps already now.

Thank for your all suggests. I try every suggest in my asp.net project. There is no problem in js side but when i use postback method consist a problem. — Kerberos, Oct 31 '09 at 17:25

score 9 · Answer 1 · edited May 23 '17 at 12:13

9

Read from this post (courtesy of jakemcgraw):

jQuery.fn.exists = function(){return jQuery(this).length>0;}

if ($('#<%=TextBox1.ClientID %>').exists()) {
    // Do something
}

edited May 23 '17 at 12:13

Community

answered Oct 31 '09 at 14:26

o.k.w

score 8 · Accepted Answer · answered Oct 31 '09 at 14:30

8

I just use directly the length property, as suggested on the jQuery FAQ:

if ($('#<%=TextBox1.ClientID %>').length) {
    // Do something
}

answered Oct 31 '09 at 14:30

score 2 · Answer 3 · answered Oct 31 '09 at 14:29

2

The simplest I can think of when using JQuery is this:

if ($("#<%=TextBox1.ClientID %>").length == 0){
        // do something here
}

answered Oct 31 '09 at 14:29

PHeiberg

score 1 · Answer 4 · answered Oct 31 '09 at 14:27

1

Checking for the selections size() would suffice.

if ($("#<%=TextBox1.ClientID %>").size() > 0) {
   alert("Object is null")
} else {
   alert("Object is exist");
}

answered Oct 31 '09 at 14:27

Martin Nycander

4 Answers4