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

Another result using just a simple "+" sign will be:

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

So something like this should work (but!):

var a=[1,2];
var b=[3,4];
a=a+','+b; // [1,2,3,4]

... but it will convert the variable a from an Array to String! Keep it in mind.