Default values

JavaScript · Unit 4: Functions

A parameter can come with a default value: rate = 20.

If you don't pass it, it uses that value. If you pass it, it uses yours.

function tip(check, rate = 20) {
  return check * rate / 100;
}

console.log(tip(200));
console.log(tip(200, 25));

Prints

40
50

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
What does this code print?
2. Predict the output
What does this code print?
3. Complete the code
Fill in the blank so the quantity is 1 when nobody says it.
4. Predict the output
What does this code print?
5. Complete the code
Fill in the blank to order the tea with 2 sugars, without changing the milk. It should print 1 2.
6. Find the bug
This function should subtract an optional discount from the price, so total(100) should give 100. Which line has the error?
7. Multiple choice
You want to be able to call pay(200) and have the tip be 20. Which definition works?
8. Put the lines in order
Put the program in order. It should print "Ava in row A".
9. Find the case that fails
tip(check, rate) should hand back the check with the tip added. If nobody says the rate, it is 20 %. Which call makes it fail?
10. Predict the output
What does this code print?

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