With a debounced function the promise returned by the function is lost so we can’t await it.

debounce is not using the promise returned by seconds, it ignores the return value of the debounced function.

src/await.js

node src/await.js

await wraps whatever you pass to it in a promise so by using it we can’t see that the debounced function actually returns undefined.

You can see the DEBOUNCE timer is completed only 9ms instead of waiting for 3 seconds as the non-debounced function does.

Initialised
DEBOUNCE: 9.749ms
PLAIN: 3.003s

src/await-fixed.js

node src/await-fixed.js

By using asyncDebounce we get a promise that will only be completed after the debounce time has passed and the function's return promise has been fulfilled.

Initialised
PLAIN: 3.002s
DEBOUNCE: 3.109s

src/then.js

node src/then.js

If we use promise.then() instead of await we can see the debounced function actually returns undefined

You can see the DEBOUNCE timer is completed only 9ms instead of waiting for 3 seconds as the non-debounced function does.

/debounce/src/then.js:9
debounced(3).then(() => console.timeEnd('DEBOUNCE'));
            ^
TypeError: Cannot read property 'then' of undefined
    at Object.<anonymous> (/debounce/src/then.js:9:13)

src/then-fixed.js

node src/then-fixed.js

Initialised
PLAIN: 3.004s
DEBOUNCE: 3.106s

A way of doing this with _.debounce is to avoid the usage of promises and return to continuation-passing style. That is the use of callbacks.

Avoiding promises also mean async/await can't be used.

src/cps.js

node src/cps.js

Initialised
PLAIN: 3.004s
DEBOUNCE: 3.104s