5 hands-on exercises and 5 find-the-bug challenges for the JavaScript Features lesson. Every one is checked automatically in the browser — write the code, run it, and the tests tell you what still fails.
A variable holds a number then a string — report the final type.
Store a function in a variable, call it, and show the result.
Build the greeting "Hello Ada" with a template literal.
Read the title property from an object and show it.
Double every number in [1,2,3] and join them with dashes.
The function itself is shown instead of its result.
Normal quotes do not interpolate the variable.
Ready to write the code?
The editor, the automatic checks and the worked solutions open up with an account.
Open the workspaceThe object has no such property, so this shows undefined.
The arrow body uses braces without a return.
This reports the type of the old value.