for...of Loops

Iterating through arrays with regular for loops is ... awkward. We have to keep track of the index, check the length, increment the index, and use the current index to get the value we actually want. Ugh.

Any time something feels that painful, there's a good chance there's an easier way. In this case, it's for...of loops.

I've rewritten multiply using a for...of loop. Isn't that much better?

• number refers to the current element -- no need to use an index to get it from of the list.
• the condition is much simpler; because we want to look at each element in the array, there's really no need to define an ending condition or update a loop variable.

Tests

Your job is to rewrite add using a for...of loop. It will need to pass the same tests that your other versions of add passed. Use multiply as a guide.