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how to make a jquery "$.post" request synchronous [duplicate]

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Is jQuery post synchronous?

post() method does it's operations asynchronously. I'm setting a variable inside the call onSuccess and the calling method doesn't get a response because of this, so all my js/jquery fails on pageLoad... I would prefer if I could still keep using the $.

Is jQuery synchronous or asynchronous?

By default jQuery is not providing synchronous request, so we have to implicitly define synchronous request using $. ajax().

How do you make AJAX request synchronous?

ajax({ type: "POST", async: "false", url: "checkpass. php", data: "password="+password, success: function(html) { var arr=$. parseJSON(html); if(arr == "Successful") { return true; } else { return false; } } }); $. ajaxSetup({async: true});

Is jQuery post asynchronous?

The jQuery post() method sends asynchronous http POST request to the server to submit the data to the server and get the response.


jQuery < 1.8

May I suggest that you use $.ajax() instead of $.post() as it's much more customizable.

If you are calling $.post(), e.g., like this:

$.post( url, data, success, dataType );

You could turn it into its $.ajax() equivalent:

$.ajax({
  type: 'POST',
  url: url,
  data: data,
  success: success,
  dataType: dataType,
  async:false
});

Please note the async:false at the end of the $.ajax() parameter object.

Here you have a full detail of the $.ajax() parameters: jQuery.ajax() – jQuery API Documentation.


jQuery >=1.8 "async:false" deprecation notice

jQuery >=1.8 won't block the UI during the http request, so we have to use a workaround to stop user interaction as long as the request is processed. For example:

  • use a plugin e.g. BlockUI;
  • manually add an overlay before calling $.ajax(), and then remove it when the AJAX .done() callback is called.

Please have a look at this answer for an example.


If you want an synchronous request set the async property to false for the request. Check out the jQuery AJAX Doc


From the Jquery docs: you specify the async option to be false to get a synchronous Ajax request. Then your callback can set some data before your mother function proceeds.

Here's what your code would look like if changed as suggested:

beforecreate: function(node,targetNode,type,to) {
    jQuery.ajax({
         url:    url,
         success: function(result) {
                      if(result.isOk == false)
                          alert(result.message);
                  },
         async:   false
    });          
}

this is because $.ajax is the only request type that you can set the asynchronousity for