DEV Community: Basit Raza

Answer: Why use `concat` instead of `push` in this instance?

Basit Raza — Tue, 06 Oct 2020 09:54:43 +0000

answer re: Why use `concat` instead of `push` in this instance?

Oct 6 '20

In simple push append the array in the same reference, while concat doestn't effect the orignal array. Check out following snippet

let x = [1,2,3,4];
let y = x.concat(5);
// At this step y hold [1,2,3,4,5] and x remain unchanged to [1,2,3,4]
document.write('x=>'+x);
document.write('y=>'+y);

let z = x.push(5);

…

Open Full Answer

Answer: Using Mongoose `pre` hook to get document before findOneAndUpdate()

Basit Raza — Fri, 04 Sep 2020 13:06:43 +0000

answer re: Using Mongoose `pre` hook to get document before findOneAndUpdate()

Feb 7 '19

You can't retrieve the document in the pre hook.

According to the documentation pre is a query middleware and this refers to the query and not the document being updated.

Open Full Answer