Jquery: Return data after ajax call success

javascript

promises

callbacks

async-await

byAlex Kataev·Dec 11, 2024

Your primary tools for asynchronous data retrieval with jQuery AJAX are promise callbacks such as .done(), or you own defined success callbacks for handling received data.

Leveraging promises:

$.ajax({url: 'your-endpoint'}).done(data => console.log('Data:', data));

Applying success callback:

$.ajax({
  url: 'your-endpoint',
  success: data => console.log('Data:', data)
});

While both methods will display data when the AJAX request is successful, neither of them can return it in the conventional sense due to the asynchronous nature of AJAX.

Unraveling Promises and Callbacks

When mastering $.ajax, bear in mind you are engaging with asynchronous operations. These operations don't obstruct execution flow, meaning your callbacks and promises must adapt to handle asynchronous data.

Unleashing the power of Promises

Promises gift your code with elegance and a modern touch. Encase your $.ajax within a function that yields a promise:

function makeAjaxCall(url) {
  // Who needs a magic ball when you have promises?
  return Promise.resolve($.ajax({url: url}));
}

makeAjaxCall('your-endpoint').then(data => {
  // Party with your data here
});

Embracing the async/await symphony

Enrich your promise code with async and await for improved readability and flow control. It allows you to handle asynchronous calls as if they are synchronous:

async function getData(url) {
  // Await: the closest thing we have to time travel 
  return await Promise.resolve($.ajax({url: url}));
}

// Usage
(async () => {
  try {
    const data = await getData('your-endpoint');
    console.log('Async/Await Data:', data);
  } catch (error) {
    console.error('There was an error!', error);
  }
})();

Note: Depending on your environment, you may need to use a transpiler (Babel) or a generator-based approach for async and await support.

Mastering the Error Realm

While capturing successful data returns is critical, never underestimate the value of robust error handling:

$.ajax({
  url: 'your-endpoint'
}).done(data => {
  // Handle a bounty of success
}).fail(error => {
  // Treat this error like a teaching moment
});

Navigating the Wild Waters of Asynchronicity

Cramming a return data statement directly into an AJAX call frequently leads to shipwrecks due to the asynchronous execution. Instead of plotting a collision course, navigate delicately around the islands of asynchronicity by using callbacks or promises.

Using callbacks as our compass

function testAjax(url, handleData) {
  $.ajax({
    url: url,
    success: function(data) {
      // Callbacks: A guiding light through the async sea.
      handleData(data);
    }
  });
}

// Usage
testAjax('your-endpoint', function(output) {
  // It's like unwrapping a gift
});

Sailing with async in view

Embrace asynchronous patterns throughout your coding journey:

Dock results where data's scope is accessible.
Avoid the siren’s call of deprecated async: false: it leads to browser block and terrible user experiences.
Use async seafaring tools .then(), .done(), and .fail() for smooth and bold promise navigation.

Expanding Horizons with Callbacks and Promises

Unlocking the might of callbacks

Callbacks, the trusty tools for handling asynchronous operations, are basically functions passed inside other functions. The latter only run after the async task concludes:

function handleData(data) {
  // Data AI: Assemble!
}

$.ajax({
  url: 'your-endpoint',
  success: handleData
});

Pioneering with promises

Promises let you cleanly handle both success and error states, keeping your sanity in check:

let ajaxPromise = $.ajax({ url: 'your-endpoint' });

ajaxPromise.then(
  data => {
    // Success feels sweet, doesn't it?
  },
  error => {
    // It's not an error, it's a learning opportunity
  }
);

async/await and the art of error capture

With async and await, you capture errors while preserving the synchronous look:

async function requestData(url) {
  try {
    return await $.ajax({ url: url });
  } catch (error) {
    // An error a day keeps the doctor at bay (not medical advice!)
  }
}