I'm going through and assignment from eloquent JS book, and I'm super confused! The point is to compare 2 objects.

1. What's going on here: !deepEqual(a[key], b[key]) ? Why do I need to run the recursion on the object values?

2. Why a.key and b.key break the code?

3. If I remove the if (a === b) return true; line - the code breaks? I thought I'm dong the deep comparison.

function deepEqual(a, b) {
    if (a === b) return true;

    if (a == null || typeof a != "object" ||
        b == null || typeof b != "object") return false;

    let keysA = Object.keys(a), keysB = Object.keys(b);

    if (keysA.length != keysB.length) return false;

    for (let key of keysA) {
        if (!keysB.includes(key) || !deepEqual(a[key], b[key])) return false;
    }

    return true;
}

let obj = { here: { is: "an" }, object: 2 };
console.log(deepEqual(obj, obj));
// → true
console.log(deepEqual(obj, { here: 1, object: 2 }));
// → false
console.log(deepEqual(obj, { here: { is: "an" }, object: 2 }));
  // → true