javascript - Why push does not working with set methond in Map object

Question

So very quick question here which I wasn't able to get sorted when searching google.

I have some code that works which has a Map object this.tweet and a (key,value) of (string,array). I push a value into the array and re-set Map object.

    const newTweet = this.tweet.get(tweetName) || [];
    newTweet.push(time);
    this.tweet.set(tweetName, newTweet);

However, I am a minimalist freak and want a one-liner. When I want to add something to the array, I was wondering why I am not able to do this

this.tweet.set(tweetName, newTweet.push(time));

I keep getting a newTweet.push(time) is not a function error.

Thanks

question from:https://stackoverflow.com/questions/66068551/why-push-does-not-working-with-set-methond-in-map-object

Answer 1

Look at some documentation for push

The push() method adds one or more elements to the end of an array and returns the new length of the array.

Since you want to pass the array to set you can't use the return value of push.

---

You could create a completely new array instead:

const newTweet = this.tweet.get(tweetName) || [];
this.tweet.set(tweetName, [...newTweet, time]);