A rejection occurs if the function encounters an error.

A resolution is similar to a return statement but can be invoked at any time meanwhile, JavaScript continues executing the rest of the code. A Promise says, “I promise I will have a response for you soon but don’t wait I’ll tell you when I’m ready.” The response can either be a resolution or a rejection. The r3bl-ts-utils package is a set of useful TypeScript functions and classes that can be used in Node.js and browser. JavaScript Promises allow you to avoid blocking code. For these 5 seconds, the site will not be changing the background color. In a single-threaded application, you would have to wait 5 seconds for the API to respond, then resume changing the site’s background color. Just put the code you want to delay in the callback. You have some other JavaScript code that should constantly change the webpage’s background color. One way to delay execution of a function in NodeJS is to use the seTimeout () function. At the same time, you still require other parts of your code to be executed.įor example, say you are making an API call that takes about 5 seconds to come back with a response. Use the await() Keyword to Pause Execution of Codes in Node. Every so often, you may want to accept user input, wait for an event to be triggered, or make an API call. JavaScript Promises are unique objects that define a function to execute. It is a one-liner! But if you are unfamiliar with async functions, you might need an explainer.

Demo of the sleep function in NodeJS (also works in the browser)

Node js sleep await