post.comments = post.comments.filter( ({ id }) => id !== req.params.comment_id ); -->Working of code

Question

I am getting hard time understanding this code , I looked through internet but still couldn't get it.

post.comments = post.comments.filter(
  ({ id }) => id !== req.params.comment_id
);

I want to know how this code is actually working.

Which part is not clear? There are at least three different things here. — VLAZ, Apr 01 '20 at 08:37
@YogeshwarSherawat it's an arrow function and return `true` or `false`. — Mahdi Aslami Khavari, Apr 01 '20 at 08:40
https://stackoverflow.com/questions/24900875/whats-the-meaning-of-an-arrow-formed-from-equals-greater-than-in-javas https://stackoverflow.com/questions/10804982/where-can-i-get-info-on-the-object-parameter-syntax-for-javascript-functions — VLAZ, Apr 01 '20 at 08:41

score 2 · Accepted Answer · edited Jun 20 '20 at 09:12

.filter is a function of Array and it expects a callback function which returns a boolean value.

If the callback returns true item will be added in returned array. For false, it will be skipped.

() => {} is called Arrow function, which is similar to an anonymous function but does not have context and its inherited from defining function.

({ id }) is a called as destructuring assignment where you can cherry-pick any property and create variable for it.

So the object comment instide post.comments will have id property and you are just fetching it from object

Your code would look something like this in ES5

post.comments = post.comments.filter(function(comment) {
  var id = comment.id;
  return id !== req.params.comment_id;
})

1 Answers1