JS Array a['1'] doesnot gives an error

Question

I have declared an array a = [1,2,3,4,5]

When I write a[1] it returns 2 which is perfectly fine but when I write a[\'1\']

Answer 1

First of all, array is also object having property names as 0,1,2,....n

Property names must be strings. This means that non-string objects cannot be used as keys in the object. Any non-string object, including a number, is typecasted into a string via the toString method. [Ref]

Answer 2

In JS an Array is basically an Object and thus mostly behaves like one. In this case, these are equivalent as long as you dont access Array's .length or try iterating a:

const a = {"0": foo};    
const b = ["foo"];

Also this would work:

const a = ["foo"];
a.bar = "baz";

console.log(a);

So that a[1] and a['1'] are equivalent is exactly what's to be expected.

Answer 3

All property names are strings.

If you pass a number, it gets converted to a string before being used to look up the property value.

console.log(1 == '1');