Should I use return before resolve / reject in ES6 Promise?

Question

Is it more correct to use return when calling resolve / reject for an ES6 promise? Does this help with the call stack?

return new Promise((resolve, reject) => {           
this._mariadb.query(...,
    (err, rows) => {             
            if (err) {return reject(err);}                
            if (rows.info.numRows > 0) {return resolve(true);}        
            return resolve(false);                
        });            
    });

score 3 · Answer 1 · answered May 16 '16 at 16:03

The return value isn't used but it can be a quick way to exit the function early. That's all. The code you have above could be written to function the exact same way without return

if (err)
  reject(err);
else if (rows.info.numRows > 0)
  resolve(true);
else
  resolve(false);

Or even better

if (err)
  reject(err);
else
  resolve(rows.info.numRows > 0);

score 2 · Answer 2 · answered May 16 '16 at 15:52

2

return reject(err) is just a more concise (but also more confusing) way to say reject(err); return. The argument of the Promise ("executor") isn't supposed to return anything meaningful, so no, it's doesn't matter if you use return or not.

answered May 16 '16 at 15:52

georg

211,518
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score -1 · Answer 3 · answered May 16 '16 at 17:01

-1

No, you shouldn't because once promise is resolved/rejected it is never change state

answered May 16 '16 at 17:01

maxpolski

11
1
3

Should I use return before resolve / reject in ES6 Promise?

3 Answers3