Append array at the beginning of the array of objects - Javascript

Question

I'm using react js on this but I think this one is a Vanilla Javascript question. What I want to achieve here is to push an array at the beginning of the lists of objects. current what I have is to append at the end of the object using concat:

this.setState({
            lists: this.state.lists.concat([result])
        });

How can I implement to push at the beginning of the array. This is what the data that will be push at the beginning:

In my opinion it's not a generic JS question, because when you're talking about React state, you usually don't want to mutate your data. That's why using a simple this.state.lists.unshift(result) is not the best thing you can do even though it works to some extent. — Tomasz Lenarcik
– Tomasz Lenarcik, Commented Dec 27, 2016 at 9:26

Tomasz Lenarcik · Accepted Answer · 2016-12-27 09:19:44Z

4

I think that what you want is probably:

this.setState({
    lists: [result].concat(this.state.lists),
});

But if you're using ES6, there's also a nicer way:

this.setState({
    lists: [result, ...this.state.lists],
});

answered Dec 27, 2016 at 9:19

Tomasz Lenarcik

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