Asynchronous Programming in JavaScript: async and await

Instead of using promises for async tasks, you can do the same thing using the new async and await keywords in JavaScript.

Consider this method:

    main(a) {
        return Promise.resolve(a)
        .then(a => asyncTaskA(a))
        .then(b => asyncTaskB(b))
        .then(c => asyncTaskC(c))
        .catch(e => console.log(e))
        .finally(() => cleanUp());
    }

You can rewrite it much simpler in this way:

    async main(a) {
        try {
            let b = await asyncTaskA(a);
            let c = await asyncTaskA(b);
            return await asyncTaskA(c);
        } catch (e) {
            console.log(e)
        }
        cleanUp();
    }

This is certainly a more elegant and simpler approach for writing async code.

It should be remembered that await can only be used inside a function that has been marked with the async keyword. This keyword shows that the function returns a promise and thus is an async function.