Is JavaScript array index a string or an integer?

Question

I had a generic question about JavaScript arrays. Are array indices in JavaScript internally handled as strings? I read somewhere that because arrays are objects in JavaScri

Answer 1

Let's see:

[1]["0"] === 1 // true

Oh, but that's not conclusive, since the runtime could be coercing "0" to +"0" and +"0" === 0.

[1][false] === undefined // true

Now, +false === 0, so no, the runtime isn't coercing the value to a number.

var arr = [];
arr.false = "foobar";
arr[false] === "foobar" // true

So actually, the runtime is coercing the value to a string. So yep, it's a hash table lookup (externally).