Why is [1,2] + [3,4] = “1,23,4” in JavaScript?

Question

I wanted to add the elements of an array into another, so I tried this:

[1,2] + [3,4]

It responded with:

\"1,23,4\"
         


        

Answer 1

The + concats strings, so it converts the arrays to strings.

[1,2] + [3,4]
'1,2' + '3,4'
1,23,4

To combine arrays, use concat.

[1,2].concat([3,4])
[1,2,3,4]