jQuery Check if div with certain class name exists

Question

Using jQuery I m programmatically generating a bunch of div s like this    lt div class  mydivclass  id  myid1  gt Some Text1 lt  div gt   lt div class  mydivclass  id  myid2  gt Some Text2 lt  div gt    Somewhere else in my code I need to detect if these DIVs exist  The class name for the divs is the same but the ID changes for each div  Any idea how to detect them using jQuery

User · Answer

Here are some ways   1   if    div   hasClass  mydivclass           Your code        It returns true if any div has  mydivclass  name  It is a based on the class name        2  if     myid1   hasClass  mydivclass           Your code           It returns true if specific div myid1  has this class  mydivclass  name           It is a  based on the specific div id s                   3  if    div class  mydivclass     length  gt  0         Your code        It returns all the divs whose class name is  mydivclass         and it s length would be greater than one          We can use any one of the abobe defined ways based on the requirement

User · Answer

You can use size    but jQuery recommends you use length to avoid the overhead of another function call      div mydivclass   length   So      since length is zero  it evaluates to false if     div mydivclass   length      http   api jquery com size   http   api jquery com length   UPDATE  The selected answer uses a perf test  but it s slightly flawed since it is also including element selection as part of the perf  which is not what s being tested here  Here is an updated perf test   http   jsperf com check-if-div-exists 3  My first run of the test shows that property retrieval is faster than index retrieval  although IMO it s pretty negligible  I still prefer using length as to me it makes more sense as to the intent of the code instead of a more terse condition

User · Answer

check if the div exists with a certain class  if      mydivclass   length  gt  0    it exists

User · Answer

Here is a solution without using Jquery  var hasClass   element classList contains  class name to search       hasClass is boolean if hasClass     true            Class exists     reference link

User · Answer

Here is very sample solution for check class  hasClass  in Javascript   const mydivclass   document querySelector   mydivclass       if  hasClass  is exist on  mydivclass  if mydivclass classList contains  hasClass            do something if  hasClass  is exist

User · Answer

In Jquery you can use like this  if     quot  className quot   0           Do something if class exists    else       Do something if class does not exist     With JavaScript if  document getElementsByClassName  quot className quot   length  gt  0        Do something if class exists   else          Do something if class does not exist

User · Answer

You can simplify this by checking the first object that is returned from JQuery like so   if      mydivclass   0           Do something if class exists   else          Do something if class does not exist     In this case if there is a truthy value at the first   0   index  then assume class exists   Edit 04 10 2013  I ve created a jsperf test case here

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To test for div elements explicitly   if     div mydivclass   length

User · Answer

if     myClass   0     undefined        it exists  else       does not exist

User · Answer

if      mydivclass   size           code here     The size   method just returns the number of elements that the jQuery selector selects - in this case the number of elements with the class mydivclass  If it returns 0  the expression is false  and therefore there are none  and if it returns any other number  the divs must exist

User · Answer

Use this to search whole page  if        hasClass  mydivclass        Do Stuff

User · Answer

It s quite simple     if      mydivclass   length  gt  0        do something

User · Answer

The simple code is given below    if      mydivclass   length  gt  0         Things to do if class exist     To hide the div with particuler id    if        given id   mydivclass   length  gt  0         Things to do if class exist

User · Answer

div   hasClass  mydivclass     Returns true if the class exist

User · Answer

if     quot  myid1 quot   hasClass  quot mydivclass quot       Do any thing

User · Answer

var x   document getElementsByClassName  class name    if  x 0     alert  has      else   alert  no has

User · Answer

The best way in Javascript       if  document getElementsByClassName  search-box   length  gt  0       do something

User · Answer

Without jQuery  Native JavaScript is always going to be faster  In this case   example  if  document querySelector   mydivclass       null              it exists     If you want to check to see if a parent element contains another element with a specific class  you could use either of the following   example  var parent   document querySelector   parent     if  parent querySelector   child       null              it exists as a child    Alternatively  you can use the  contains   method on the parent element   example  var parent   document querySelector   parent        child   document querySelector   child     if  parent contains child               it exists as a child       and finally  if you want to check to see if a given element merely contains a certain class  use  if  el classList contains className               el contains the class

[javascript] jQuery: Check if div with certain class name exists

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