Recently, when I was working on my practice project Microsoft Todo Clone, I needed to implement code like this:
#1 Do Task 1
#2 Wait for 200ms
#3 Do task 2
#4 Wait for 200ms
#5 Do Task 3
Notice #2 and #4. They smell of setTimeout 😖. setTimeout takes in a callback, meaning there will be an indentation. Whenever those appear, means the code's gonna get ugly.
So I wrote this code in JS
doTask1();
setTimeout(() => {
doTask2();
setTimeout(() => {
doTask3();
}, 200);
}, 200);
Now you can see for yourself, this code SMELLS. BAD.
The moment I wrote it, I knew it wouldn't work in long-term. What if I needed to an extra step of waiting and doing a Task #4? Or rearranging the order.
So, I declared a utility function and it solved the problem completely.
/**
* @param {number} time Time to wait for in milliseconds
*/
function waitFor(time) {
return new Promise((resolve) => setTimeout(resolve, time));
}
Here we're returning a Promise, which resolves when the setTimeout function inside runs.
It's usage would be as simple as
await waitFor(200);
So the spaghetti code above could be rearranged like this:
doTask1();
await waitFor(200);
doTask2();
await waitFor(200);
doTask3();
See how simple it became? It reads exactly like the text version I wrote at the top. It's very idiomatic 😎.
#Shorter code
That code snippet could be simplified further
const waitFor = (time) => new Promise((resolve) => setTimeout(resolve, time));