Javascript loop through array asynchronous

Question

I'm making a bot code for a game running on NodeJS and what this function is supposed to do is to loop through an array of vectors and then make the bot go to each vector.

However, what it's actually doing is telling the bot to run to all the vectors at the same time so it spazzes out and then runs to the last vector in the array:

function digSchedule() {
    var arrayLength = blocksToMine.length;
    for (var i = 0; i < blocksToMine.length; i++) {
        console.log(i);
        scaffoldTo(blocksToMine[i]);
    }
    ...
}

The function scaffoldTo() needs to be ran and then wait for the bot to do said function then run it for the next element in the array, but I can't figure out how to do it.

Answer 1

There's several ways to achieve this. The first is probably to pass a callback with the "next function to be called" (probably scaffoldTo()). You can use .bind() to create a reference with the iterator index i.

Alternatively, you could set up a loop of Promises, which by definition have a .then() method which executes once the promise is resolved.

Finally, the async/await pattern is similar to Promises, but some find it clearer and it seems to be winning the Hype Wars: https://hackernoon.com/6-reasons-why-javascripts-async-await-blows-promises-away-tutorial-c7ec10518dd9.

Callbacks (solution 1) will be available in any version of JS. Promises generally available with a library and have native support in ES6. Async/await is a proposal (?) in ES2017 and is generally well supported.