Sorting like at work

JavaScript · Unit 22: Searching and sorting

In a real job nobody writes selection sort or merge sort by hand: sort and toSorted ship with the language, tuned by a lot of people over years.

What you do write is the comparator. And if you give it a name, you can reuse it on every list you want.

const smallFirst = (a, b) => a - b;
const ns = [40, 10, 30];
const o = ns.toSorted(smallFirst);
console.log(o, ns);

Prints

[ 10, 30, 40 ] [ 40, 10, 30 ]

The rest of the explanation is in the lesson, which is part of the full plan.

Exercises in this lesson

You do them in the app, which checks them on the spot and explains why.

1. Predict the output
flipped uses the comparator next to it, with the arguments swapped. What does it print?
2. Complete the code
Complete it so that, on equal points, whoever has fewer fouls comes first.
3. Predict the output
The tiebreak is alphabetical. What does it print?
4. Multiple choice
This comparator is wrong. Why?
5. Find the bug
The prices should come out from smallest to largest, that is [ 9, 10, 100 ]. Which line has the error?
6. Predict the output
Two people tie on points and the comparator only looks at points. What does it print?
7. Put the lines in order
Put in order the function that returns the names from most points to fewest, without shuffling the list it receives.
8. Find the case that fails
best(js) returns the name of whoever has the most points, or "nobody" if the list is empty. On a tie, whoever came first wins. Which call does it fail on?
9. Multiple choice
Now that you've written your own sorts, when is it worth using them in a real program?

It opens in your browser. This lesson is part of the full plan; the first unit of each course is free.