How to Create an Async Function

Publikováno: 24.9.2020

One thing I love about JavaScript is that there are many ways to accomplish the same task, one such example being creating functions. There are several patterns for functions; one of the last you see used is the new Function method: /* new Function(arg1, arg2 (...), body) */ const myFunction = new Function('users', 'salary', 'return […]

The post How to Create an Async Function appeared first on David Walsh Blog.

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One thing I love about JavaScript is that there are many ways to accomplish the same task, one such example being creating functions. There are several patterns for functions; one of the last you see used is the new Function method:

/* new Function(arg1, arg2 (...), body) */
const myFunction = new Function('users', 'salary', 'return users * salary');

What if you want to use this new Function method to create an async function? You need to be a bit clever, and thanks to MDN, we have an answer:

// Shim for allowing async function creation via new Function
const AsyncFunction = Object.getPrototypeOf(async function(){}).constructor;

// Usage
const fetchPage = new AsyncFunction("url", "return fetch(url);");
fetchPage("/").then(response => { ... });

The usage of Object.getPrototypeOf(async function(){}).constructor is super clever, as a native AsyncFunction doesn’t exist. I don’t believe that I’ve ever used the new Function pattern but that doesn’t mean you don’t! And now you can make them asynchronous!

The post How to Create an Async Function appeared first on David Walsh Blog.

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