How to make this promise work?

Question

https://code.sololearn.com/WmPsa0owcri0/?ref=app

Answer 1

something like this, only call res when you think the function should return. if it should return after waiting in set timeout, then call it when the timeout done

setTimeout(()=>{res("Task Complete")},3000);

same applied with rej/reject, call it only when the function cannot continue. maybe in case of Exception or something

Answer 2

Try using setTimeout in a different way:

setTimeout(() => {
res("Task completed");
}, 3000);

Answer 3

Sameer Crestha For your example of using Promise with setTimeout, you only need to call res("message to show"); in the callback of setTimeout for successfully execution, if errors, call ref("error") function instead.

function waitsthreesec(){
return new Promise((res,rej)=>{
let isDone;
setTimeout(()=>{
let err;
// processing data, set err = true if error encountered

if(err) rej("Error"); // this would pass the arg to and run .catch function
else res("timer message"); // this would pass the arg to and run .then function

},3000);//a task that will take 3 second to complete
});

}
waitsthreesec().then(msg=>{console.log(msg)}).catch(err=>{console.log(err)});

Answer 4

It has do with how events work in js ,they are asynchronously executed and that is what is happening inside the promise ,your setTimeout executes after 3 seconds but if and else are executed immediately ,and so task is rejected ,all you need to do is put those if else inside setTimeout