CodeParkfunction Team() {}
Team.prototype.members = [];
const a = new Team();
const b = new Team();
a.members.push("Ann");
a.tags = ["x"];
console.log(b.members.length, b.tags);
1 undefined
The answer is 1 undefined. a.members.push reads members through the prototype chain. It changes the single array stored on the prototype, so b sees Ann too. Assigning a.tags creates an own property on a only, so b.tags is undefined.
The tempting option "0 undefined" is wrong because push does not create a new array on a. It changes the shared one. This is why changeable state belongs in the constructor, not on the prototype.
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