Efficient Methods for Knowing When jQuery AJAX Calls Are Done

1. Using $.ajaxStop():

   • This method attaches a function to be executed whenever all ongoing AJAX requests complete.
   • It's a global approach, applicable to all AJAX calls made throughout your application.

   $(document).ajaxStop(function() {
     // Code to execute when all AJAX calls are finished
     console.log("All AJAX calls completed!");
   });
   

2. Using Promises (Preferred):

   • This method leverages the asynchronous nature of AJAX requests effectively.
   • You can chain multiple .done() (success) or .fail() (error) handlers to each individual AJAX call and create a larger "master" promise:

   var allRequestsDone = $.when(
     $.ajax(url1), // First AJAX call
     $.ajax(url2), // Second AJAX call
     // ... more AJAX calls
   );
   
   allRequestsDone.done(function() {
     // Code to execute when all AJAX calls are finished, regardless of individual success/failure
     console.log("All AJAX calls completed!");
   });
   
   allRequestsDone.fail(function() {
     // Code to handle if any AJAX call fails
     console.error("An error occurred in one or more AJAX calls");
   });
   

3. Using a Counter (Less Preferred):

   • While not the most elegant solution, you can maintain a counter to track ongoing AJAX requests:

   var activeRequests = 0;
   
   function incrementRequests() {
     activeRequests++;
   }
   
   function decrementRequests() {
     activeRequests--;
     if (activeRequests === 0) {
       console.log("All AJAX calls completed!");
     }
   }
   
   // Wrap your AJAX calls with these methods:
   incrementRequests();
   $.ajax(url, {
     success: function() {
       decrementRequests();
     },
     error: function() {
       decrementRequests(); // Handle error
     }
   });
   

Choosing the Best Method:

• $.ajaxStop(): For simple scenarios where you need to know only when all calls have finished, regardless of individual success/failure.
• Promises: For better control over individual call results and chaining actions. (Consider this the recommended approach.)
• Counter: As a last resort if you have limited control over the specific number of AJAX calls being made.

• The always() method within each individual AJAX call is executed regardless of success or failure. This allows you to perform common actions, like hiding loading indicators, after each call finishes. You can track the completion status internally within this method.

var completedRequests = 0;
var totalRequests = 3; // Set the total number of expected calls

function makeAjaxCall(url) {
  $.ajax({
    url: url,
    success: function() {
      // Success logic
    },
    error: function() {
      // Error handling
    },
    always: function() {
      completedRequests++;
      if (completedRequests === totalRequests) {
        console.log("All AJAX calls completed!");
      }
    }
  });
}

makeAjaxCall(url1);
makeAjaxCall(url2);
makeAjaxCall(url3);

Combining $.ajax() with a deferred object:

• Create a deferred object using $.Deferred(). This allows you to chain AJAX calls and execute code only when all calls are resolved (completed).

var deferred = $.Deferred();
var numCalls = 2; // Set the number of calls

function makeAjaxCall(url) {
  $.ajax({
    url: url,
    success: function() {
      deferred.notify(); // Notify progress for each completed call
    },
    error: function() {
      deferred.reject(); // Reject on error
    }
  });
}

makeAjaxCall(url1);
makeAjaxCall(url2);

deferred.done(function() {
  if (arguments.length === numCalls) { // Check if all calls completed successfully
    console.log("All AJAX calls completed successfully!");
  }
});

deferred.fail(function() {
  console.error("Error in one or more AJAX calls");
});

• always(): Suitable for basic completion tracking within individual calls, combined with a separate counter if needed.
• $.Deferred(): Useful for chaining calls and handling individual successes/errors, offering more control.