JuniorTheoryCommon

What does the program print?

JavaScript

const a = [1, 2];
const b = a;
b.push(3);

console.log(a.length, a === [1, 2, 3]);

3 false

Expecting b = a to copy the array: both names point to one array, so b.push(3) changes a too and a.length is 3.
Expecting === to compare the elements: for arrays it checks whether both sides are the same array, and [1, 2, 3] is a new one, so it is false.