5 hands-on exercises and 5 find-the-bug challenges for the JavaScript Map lesson. Every one is checked automatically in the browser — write the code, run it, and the tests tell you what still fails.
Put a score in a Map and read it back.
Report how many entries the Map holds.
Store a value under a numeric key and read it back.
Delete an entry and report whether it is still there.
Create a Map from pairs and read one value.
An object turns every key into a string.
size is a property, not a method.
Ready to write the code?
The editor, the automatic checks and the worked solutions open up with an account.
Open the workspaceA Map is read with get, not with square brackets.
A Map is built from pairs, not a flat list.
delete takes the key, not the value.