The primary function provided by async parallel is ` async.parallel `. It takes an object or an array of functions and executes them in parallel. The results are collected and passed to a final callback function once all tasks have completed. Let’s look at an example: }, 2000); }, 1500); }, 1000); task1, task2, task3 } else {

Starting with ES6, JavaScript introduced several features that help us with asynchronous code that do not involve using callbacks: Promises (ES6) and Async/Await (ES2017). Node.js® is a free, open-source, cross-platform JavaScript runtime environment that lets developers create servers, web apps, command line tools and scripts.

Use Promise.all for the parallel function calls, the answer behaviors not correctly when the error occurs. First, execute all the asynchronous calls at once and obtain all the Promise objects. Second, use await on the Promise objects. This way, while you wait for the first Promise to resolve the other asynchronous calls are still progressing.

One very common strategy is to use what Node.js adopted: the first parameter in any callback function is the error object: error-first callbacks If there is no error, the object is null. If there is an error, it contains some description of the error and other information. Callbacks are great for simple cases!