Why async await not work in forEach ?

I recently encountered a scenario where I was using async await inside forEach, but it was not working inside foreach loop.

Here is the demonstration of the problem:

asycn await not working inside forEach

In the above code, callback function passed to forEach function didn’t respected the async/await. Even though everything is right at least syntactically.

Now, lets dig deeper and try to find the cause, why asycn await didn’t work inside for Each.
The reason for this lies in the first requirement of async and await. And this requirement might not met in every cases, mostly when we are using inbuilt methods.

i.e. await must be used inside a async function.

Consider below code and let us see the order of console.logs

In the above code for Normal Flow everything is fine. Thing to pay attention is the Special Flow . We did something new there.

we used call method to call our simplePromise method. And this is the reason my code didn’t paused in Special flow . Beacuse call method directly call the method without respecting the async tasks. call method do not uses the async keyword.

And same happens in case of forEach . If we see the implementation of forEach then we will get to see this line:

callback.call(T, kValue, k, O);

We simply call the callback function and do not care about any asynchronous thing. And due to this forEach do not respect async await keyword.

Find the full Implementation of forEach here.

So what is the solution for above problem?

Simply use for loops. We can either use ancient for loop or the new for of/in loops. Any variation of these will work.

Read more about call method here.



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