Suppose you have two arrays:
const first = ['one', 'two'] const second = ['three', 'four']
and you want to merge them into one single array
How can you do so?
The modern way is to use the destructuring operator, to create a brand new array:
const result = [...first, ...second]
This is what I recommend. Note that this operator was introduced in ES6, so older browsers (read: Internet Explorer) might not support it.
If you want a solution that works also with older browsers, you could use the
concat() method which can be called on any array:
const result = first.concat(second)
Both methods will generate a new array, without modifying the existing ones.