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How to push to an array only if value doesn’t exist with JavaScript?

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Sometimes, we want to push to an array only if value doesn’t exist with JavaScript.

In this article, we’ll look at how to push to an array only if value doesn’t exist with JavaScript.

How to push to an array only if value doesn’t exist with JavaScript?

To push to an array only if value doesn’t exist with JavaScript, we use a set.

For instance, we write

const s = new Set();

s.add("hello");
s.add("world");
s.add("hello");
s.delete("world");

const array = Array.from(s);

to use the Set constructor to create a set.

Then we call add to add entries to it.

And we call delete to delete entries from it.

Next, we call Array.from to convert set s to an array.

Conclusion

To push to an array only if value doesn’t exist with JavaScript, we use a set.

By John Au-Yeung

Web developer specializing in React, Vue, and front end development.

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