由于某些原因，返回setTimeout返回1

Question

I'm trying to return setTimeout() that prints out "Hello" after .5 sec. It is returning an unwanted 1 before "Hello". Can anyone figure this out?

 let c = () => setTimeout(() => console.log("hello"), 500) console.log(c()); //1 //hello 

Answer 1

You're getting 1 because setTimeout returns its unique identifier which JS uses to identify the timeout.

This means when you console.log(c()) you're going to get the return of setTimeout which is its id.

To fix this, you can just call c() without logging its return value:

 const c = () => setTimeout(() => console.log("hello"), 500) c(); // hello