Now that we’ve covered some of the basic concepts and implementation of promises, let’s take a look at three promises gotchas that I’ve seen trip up developers as well as some tricks that might be useful.
Gotcha #1: Promise handlers return promises
If you’re returning information from a then or catch handler, it will always be wrapped in a promise, if it isn’t a promise already. You never need to write code like this:
firstAjaxCall.then(() => {
return new Promise((resolve, reject) => {
nextAjaxCall().then(() => resolve());
});
});
In the case above, since nextAjaxCall also returns a promise, you can just do this:
