How do I know if jQuery has an Ajax request pending

Question

I m having some problems with a jQuery control we made  Suppose you have a dropdownlist that allows you to enter the ID of the item you re looking for  and when you press ENTER or lose focus in a textbox it validates via jQuery that the ID you entered is correct  showing an alert if it doesn t   The thing is that when an ordinary user enters an invalid value in it and loses focus by pressing the submit button  the jQuery post returns after the submit of the form has been sent   Is there any way that I can check if there s any Async request processing by jQuery so that I do not allow the form submit

User · Accepted Answer

You could use ajaxStart and ajaxStop to keep track of when requests are active

User · Answer

function              function checkPendingRequest                 if    active  gt  0                    window setTimeout checkPendingRequest  1000                     Mostrar peticiones pendientes ejemplo      control   val  Peticiones pendientes      active                             else                    alert  No hay peticiones pendientes                                       window setTimeout checkPendingRequest  1000

User · Answer

The   ajax   function returns a XMLHttpRequest object  Store that in a variable that s accessible from the Submit button s  OnClick  event  When a submit click is processed check to see if the XMLHttpRequest variable is   1  null  meaning that no request has been sent yet  2  that the readyState value is 4  Loaded   This means that the request has been sent and returned successfully   In either of those cases  return true and allow the submit to continue  Otherwise return false to block the submit and give the user some indication of why their submit didn t work

User · Answer

active returns the number of active Ajax requests   More info here

User · Answer

We have to utilize   ajax abort   method to abort request if the request is active  This promise object uses readyState property to check whether the request is active or not    HTML   lt h3 gt Cancel Ajax Request on Demand lt  h3 gt   lt div id  test  gt  lt  div gt   lt input type  button  id  btnCancel  value  Click to Cancel the Ajax Request    gt    JS Code    Initial Message var ajaxRequestVariable      test   html  Please wait while request is being processed         Event handler for Cancel Button     btnCancel   on  click   function    if  ajaxRequestVariable     undefined   if  ajaxRequestVariable readyState  gt  0  amp  amp  ajaxRequestVariable readyState  lt  4      ajaxRequestVariable abort          test   html  Ajax Request Cancelled              Ajax Process Starts ajaxRequestVariable     ajax               method   POST               url    echo json                contentType   application json               cache  false              dataType   json               data            json  JSON encode            data                                               prop1   prop1Value                          prop1   prop2Value                                                    delay  11                     success  function  response                    test   show                    test   html  Request is completed                                          error  function  error                                complete  function

[jquery] How do I know if jQuery has an Ajax request pending?

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