Javascript - deepEqual Comparison

Question

Question (From Eloquent Javascript 2nd Edition, Chapter 4, Exercise 4):

Write a function, deepEqual, that takes two values and returns true only if th

Answer 1

I am quite new to JS but this is the way I solved it:

function deepEqual(obj1, obj2) {
if (typeof obj1 === "object" && typeof obj2 === "object") {
    let isObjectMatch = false;
    for (let property1 in obj1) {
        let isPropertyMatch = false;
        for (let property2 in obj2) {
            if (property1 === property2) {
                isPropertyMatch = deepEqual(obj1[property1], obj2[property2])
            }

            if(isPropertyMatch){
                break;
            }
        }

        isObjectMatch  = isPropertyMatch;

        if (!isObjectMatch) {
            break;
        }
    }

    return isObjectMatch;
} else {
    return obj1 === obj2;
}
}

And here are my tests:

var 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
console.log(deepEqual(obj, {object: 2, here: {is: "an"}}));
// → true
console.log(deepEqual(obj, {object: 1, here: {is: "an"}}));
// → false
console.log(deepEqual(obj, {objectt: 2, here: {is: "an"}}));
// → false
console.log(deepEqual(2, 2));
// → true
console.log(deepEqual(2, 3));
// → false
console.log(deepEqual(2, null));
// → false
console.log(deepEqual(null, null));
// → false
console.log(deepEqual(obj, null));
// → false

Answer 2

Feel that this version is a bit more readable (easier to comprehend). The logic is very similar with the top answer though. (ES6 this time)

function deepEqual(obj1, obj2) {

    if(obj1 === obj2) // it's just the same object. No need to compare.
        return true;

    if(isPrimitive(obj1) && isPrimitive(obj2)) // compare primitives
        return obj1 === obj2;

    if(Object.keys(obj1).length !== Object.keys(obj2).length)
        return false;

    // compare objects with same number of keys
    for(let key in obj1)
    {
        if(!(key in obj2)) return false; //other object doesn't have this prop
        if(!deepEqual(obj1[key], obj2[key])) return false;
    }

    return true;
}

//check if value is primitive
function isPrimitive(obj)
{
    return (obj !== Object(obj));
}

By the way, there is a cheater version of deep equal which works like a charm)) However, it's approximately 1.6 times slower.

As noticed by zero298, this approach is sensitive to the properties ordering and shouldn't be taken seriously

function cheatDeepEqual(obj1, obj2)
{
    return JSON.stringify(obj1) === JSON.stringify(obj2);
}