resolve vs return promise js
In simple terms, inside a then handler function:
A) When x is a value (number, string, etc):
- return x is equivalent to return Promise.resolve(x)
- throw x is equivalent to return Promise.reject(x)
B) When x is a Promise that is already settled (not
pending anymore):
- return x is equivalent to return Promise.resolve(x),
if the Promise was already resolved.
- return x is equivalent to return Promise.reject(x),
if the Promise was already rejected.
C) When x is a Promise that is pending:
- return x will return a pending Promise, and it will
be evaluated on the subsequent then.
Read more on this topic on the Promise.prototype.then() docs.