Advanced Async and Concurrency Patterns in JavaScript
Async and concurrency are two of the most important features in JavaScript. Async allows us to run multiple tasks in parallel, while concurrency allows us to run multiple tasks at the same time.
Async is implemented using the Promise object. A Promise is an object that represents the result of an asynchronous task. It has two methods, then and catch. The then method is used to execute a function when the task is completed, and the catch method is used to handle any errors that occur.
The following code shows how to use the then and catch methods.
var promise = getData(); promise.then(function(data) { // do something with the data }, function(error) { // handle the error });
The concurrency feature is implemented using the Event Loop. The Event Loop is a mechanism that allows us to run multiple tasks at the same time. It works by creating a queue of tasks, and then running them one at a time.
The following code shows how to use the Event Loop.
var tasks = []; // add tasks to the queue tasks.push(function() { // do something }); // run the tasks EventLoop.run(tasks);
The following example shows how to use the Event Loop to run multiple tasks at the same time.
var tasks = []; // add tasks to the queue tasks.push(function() { // do something }); // run the tasks EventLoop.run(tasks, 2);
The Event Loop can also be used to run tasks in parallel. The following code shows how to do this.
var tasks = []; // add tasks to the queue tasks.push(function() { // do something }); // run the tasks EventLoop.run(tasks, { parallel: true });
The following example shows how to use the Event Loop to run tasks in series.
var tasks = []; // add tasks to the queue tasks.push(function() { // do something }); // run the tasks EventLoop.run(tasks, { series: true });
The Event Loop can also be used to run tasks in reverse order. The following code shows how to do this.
var tasks = []; // add tasks to the queue tasks.push(function() { // do something }); // run the tasks EventLoop.run(tasks, {
