javascript - Difference between resolve and return in promise JS

Question

var p1 = new Promise (function (res, rej){
    res(42);
}).then((result) => {return result;});

**If I have ** return result,

is this promise resolved or not? What does a "resolved promise" mean?

Answer 1

Java Script is a single threaded language. This simplifies most tasks; but, it means asynchronous tasks must be handled in a callback function. A Promise is an object oriented type of callback that offers greater functionality than a simple callback function.

A resolved promise means that the then function of the promise object will be called. In your example, the promise has been resolved.

A rejected promise means that the catch function of the promise object will be called.

Returning a result in a then function, allows for chaining. Each then result can change or manipulate the result for before passing it on to the next promise in the chain.

In your example, you resolved the first promise and then returned a result for the next promise in the chain which you don't handle so effectively the returned result does nothing.