CODEWITHSUNDEEP
jqueryasynchronousappend
RSG
RSG

Reputation: 7123

Does Jquery append() behave asynchronously?

I've seen a number of posts (append supposedly immediate) with conflicting accepted answers on this. We're using JQuery 1.4 (http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/jquery-ui.min.js) and append() seems to be asynchronous, such that:

Edited to show code in context of AJAX callback

 ...
 var message = $.ajax({
   type: "GET",
   url: "/getVolumes/" +  _Id,
   async: false 
 }).responseText;
 if (parseInt(message) != 0){
   var $results = $(message);
   $MAIN_DIV.append($results);
   retrieveTargets();
 }
...    
function retrieveTargets(){
  var $targets = $(".resultTargets");
}

Executes and creates the page as expected, yet the targets query yields nothing at runtime. Running the same code in the JS console retrieves the elements as expected.

If this is the expected behavior in JQuery what's the proper way to wait until append is finished?

Upvotes: 27

Views: 21198

Answers (2)

pragman
pragman

Reputation: 1644

Try this, if things don't work after an append.

$('#dynamic-container').append(<your-content>) ;
setTimeout(function() {
    ...code which addresses elements inside #dynamic-container...
},0) ;

More Details:

  • Apparently append is synchronous
  • Apparently the DOM doesn't update synchronously, especially in Google Chrome, I faced this problem when trying to retrieve the height of a div after an append
  • My assumption was that there were browser update threads that updated asynchronously, more comments on that below, still not clear on how things work, but the solution works in all cases for me.

Upvotes: 13

RSG
RSG

Reputation: 7123

All of the comments helped track this down. I was following a red herring in the console. The problem wasn't with synchronicity, it was with the next lines:

$targets.each( function(){
  ...
  this.html();
  ...

Needed to be 

$(this).html();

In short, everyone was correct. Jquery append() behaves synchronously.

Upvotes: 29

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