async/await

• async is shorthand for "Asynchronous"
• await is shorthard for... "Await"

We use async and await for computations that may take a long time. In short, using these warns Javascript & the programmer that these operations may be "waiting" for a while, so we are explicitly waiting with await.

In our case, the operations may be slow because using internet APIs can be slow.

promises

All async functions, and functions like fetch, return a Promise instead of a value. A Promise is a guarantee that if you await the promise, you will get the data inside.

async function one() {
    return 1;
}

If we did:

let data = one();

data will be a Promise, instead of the data we actually want. If instead we do:

let data = await one();

Now data will be 1.

calling `await`

If we define our own functions, we must use async at the start of the function. Otherwise, you cannot use await within the function body, as you have not warned Javascript the operation may take a long time. The following will not work:

// Doesn't work!
function googler() {
    return await fetch("https://google.com")
}

But this does, because we've added async:

async function googler() {
    return await fetch("https://google.com")
}