How to Wait for Multiple Asynchronous Functions in JavaScript?

Waiting for Multiple Asynchronous Functions

In asynchronous programming, JavaScript provides several methods to handle the execution of multiple asynchronous functions in parallel and wait for them to complete before continuing with the program.

Manual Counter Approach

A straightforward approach is to use a manual counter that tracks the number of asynchronous calls. As each call completes, the counter is decremented. When the counter reaches zero, it indicates that all calls are complete, and you can proceed with further processing.

Using jQuery Promises

If you're using jQuery, it simplifies this task with the use of promises. Promises represent the eventual completion or failure of an asynchronous operation. Using jQuery's $.ajax() function, which returns a promise, you can collect multiple promises and use the $.when() function to wait for them all to resolve.

Using ECMAScript 6 (ES6) Promises

ES6 introduced native promises in JavaScript. Asynchronous functions can now return promises, which you can utilize to handle asynchronous operations and wait for their completion. Using the Promise.all() function, you can wait for multiple promises to resolve and collect their returned values.

Promisifying Asynchronous Operations

If you have non-promise asynchronous operations, you can "promisify" them by wrapping them in a function that returns a promise. This allows you to use the above methods with any asynchronous operation.

Using Bluebird Promises

Bluebird is a popular promise library that offers additional features. The Promise.map() function in Bluebird simplifies the process of executing multiple asynchronous functions and collecting their results.

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