How do I compare arrays in JavaScript? [duplicate]

Answer 1

That's how the equality algorithm has been specified (sec 11.9.3):

The comparison x == y, where x and y are values, produces true or false. Such a comparison is performed as follows:

1. If Type(x) is the same as Type(y), then
   • [...]
   • Return true if x and y refer to the same object. Otherwise, return false.

So the following will return true and all other equality comparisons will return false

var x = [1,2,3];
return x == x;