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Already talked about hidden elements to their Ray and why push is not always the best approach.

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But you might also have a similar question.

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For example, here we have a task right to function which will concatenate two arrays.

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And actually, you might use here put and it will be an answer.

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This is where here you can actually write a function merge arrays.

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And here we get into a race, for example, array one and array two.

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And here you might write array one bush.

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And here you spread.

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Offer a tool.

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And after this, you can just return array one.

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And actually, not a lot of people will write code like this because here you are using input and then

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US president as a tool.

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But you might think about such approach now to see the problem, we must create, first of all, our

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result.

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And here, inside the result, we need to use two arrays array one, for example, it will be just one,

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and our array to here will be, for example, two and three and no one to call our merchandise.

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And Parsons said, first of all, array one and secondly, array two.

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And let's check in console.log what we're getting.

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So first of all, result.

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Then there's a one and there's a tool aimed at loading the page and we're getting one two three one

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two three two three.

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This is exactly the problem.

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Like it wasn't previous VIDEO Bush mutates array.

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This is way here where change in array one, even if we don't want to change it.

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This is why push in this case is not the best approach.

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What we can use here instead is, say, the array conquered, which is all the approach of JavaScript

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or just to spread operated just like we did previously.

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So instead of this return and the report, we can write here, first of all, already one dot com cat

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and we have concatenate function on their right.

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And here we're spreading our array to.

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Let's check the software to load in the page.

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Here is our result one, two three.

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And here are two one one and three two two three.

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And this is exactly the correct approach because concatenate does not mutate and rape.

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In this case, it will return for us in array.

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This is why everything is fine.

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If you don't want to use the ray, come cut.

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You can always just use a spread operator.

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So here we will use array one as a spread.

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And here we are spreading as a tool and actually the result will be exactly the same.

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We're getting one two three.

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And actually, I really like this approach because it is more flexible and you can merge not only arrays

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but also objects.

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You can add new elements here, and it is more modern if you, for example, have a question to concatenate

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three arrays or more.

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It is also possible, actually, even array can cat kind of work with several arrays, as you can see

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here inside documentation.

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Here we have three different arrays and you can write first array dot com cat and then you have secondary

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and third rate.

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And actually, it will work correctly, but actually you can do exactly the same with spread.

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Here you are, spreading at a one, then array two and here Array three if you need two.

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So both variants are possible.