JavaScript: How to Make Code Wait for Asynchronous Calls with Ajax

Asynchronous calls with Ajax are a common task in modern web development, but they can present a challenge when it comes to synchronizing code execution. Fortunately, JavaScript provides a solution to this problem with the async and await keywords.

Understanding Asynchronous Calls with Ajax

When making a request with Ajax, the code execution continues without waiting for the response to be returned. This is because Ajax calls are asynchronous by default, meaning that they do not block the thread and allow the code to continue running while the request is being processed.

While this behavior is desirable in many cases, it can create problems when it comes to synchronizing code execution. For example, if you need to perform a series of operations that depend on the results of an Ajax call, you may find that the code runs out of order and produces unexpected results.

Using async/await to Synchronize Code Execution

The async and await keywords were introduced in ES2017 to make it easier to work with asynchronous code. When used together, they allow you to write asynchronous code in a synchronous style, making it easier to read and maintain.

Here's an example of how to use async and await with an Ajax call:

<script>
async function getData() {
  const response = await fetch('https://example.com/data');
  const data = await response.json();
  return data;
}

async function processData() {
  const data = await getData();
  // do something with the data
}
</script>

In this example, the getData function makes an Ajax call to retrieve data from a remote server. The await keyword is used to pause the execution of the code until the response is returned. Once the response is received, the json method is called to parse the data and return it as a JavaScript object.

The processData function then calls getData and waits for the data to be returned before continuing. This ensures that the code runs in the correct order and that the data is available when it is needed.

Conclusion

Asynchronous calls with Ajax are an essential part of modern web development, but they can create challenges when it comes to synchronizing code execution. Fortunately, JavaScript provides the async and await keywords to make it easier to work with asynchronous code in a synchronous style. By using these keywords, you can ensure that your code runs in the correct order and that your data is available when it is needed.