Comparing Objects

Look at obj1 and obj2. They're the same, right? They have the same keys and values. So why does obj1 === obj2 return false?

What happens if you compare obj1 to itself? Update the code and run it:

console.log("objects match? ", obj1 === obj1);

Curious. Very curious.

When you compare two objects, the JavaScript engine compares the address where each is stored in memory. While the content of obj1 and obj2 is identical, they are two separate objects stored at two different memory addresses.

Tests

So how can we decide if two objects have identical content? Let's write a function that compares the content of two objects.

1. Create a function called compareObjects. It should take two arguments: first and second.
2. Inside the function body, let's first make sure they have the same number of keys. Use Object.keys to get the keys of each object and compare their lengths. If they don't match, return false.
3. Next, iterate over the keys of the first object. For each key, compare the value of the first object to the value of the second object. If they don't match, return false.
4. Finally, if we get past both the key length check and the value checks, return true. The content of the two objects is identical.

You can test your function by comparing obj1 and obj2. It should return true. Try modifying obj2 so that it no longer matches obj1 and run them through compareObjects again. This time, it should return false.