…by using Promise.all([]).
But wait, there is another less known way!
Say you have 2 asynchronous functions that take 4 seconds to resolve (2 seconds each).
For testing purposes we can ‘artificially’ create these 2 functions by using new Promise
and making them return after 2 seconds by using setTimeout(() => {...}, 2000).
So:
Now, usually if you use async/await (which you should :), you would do:
By doing that, promise2 has to ‘await’ 2 full seconds before it starts to execute and resolve after 2 other seconds.
The whole operation lasts 4 unnecessary seconds.
How can you make both async functions start executing at the same time, or in other words make them run in parallel?
By calling them, before ‘awaiting’ them:
You can test this yourself. Copy the code and paste it in your console.