Typescript Array insert non-duplicate item

Question

We are in 2016, so, I would like to know the best way to insert a non-duplicate item into an array taking into account performance and clean code.

EDIT:

For example:

My object is:

obj = {id: 1, a: 2, b: 3, c: 4}

My array arr:

arr.push(obj);

arr.push(obj); // Avoid this duplicate obj

Thank you.

You need to more specific, e.g. what identifies a duplicate item. — Sebastian Sebald
– Sebastian Sebald, Commented Oct 24, 2016 at 9:32

Sebastian Sebald · Accepted Answer · 2016-10-24 12:02:27Z

2

There is no native pushIfUnique in the language, so you have to options:

(1) If ordering is not important just use a Map an the id (or whatever) as identifier.

(2) If ordering is important you can write a small helper function by using Array.find. E.g.:

const pushIfUnique = (predicate, object, array) => {
  if (!array.find(item => predicate(object, item))) {
    array.push(object);
  }
};

answered Oct 24, 2016 at 12:02

Sebastian Sebald

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2 Comments

Sebastian Sebald Over a year ago

Well, if you only use a property subset to identify an object (= unique because of id for example) I guess Set will not have any benefits for you, b/c has only works with the whole stored value. So you would have to iterate over the entries anyway.

Eusthace Over a year ago

Ahh, you're amazing! Thank you!

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