Write down the input contract and the failure cases before coding.
tests
RUNTIME OUTPUT
Ready to run the file open above against 1 test.
Runs the open file in a restricted browser worker
LEARN FROM THE SOLUTION
Why the solution works.
Amounts remain integers from input through output, which avoids errors such as 0.1 + 0.2. The reducer makes the validation rule local to every line and keeps the input untouched.
What this exercise teaches
Array reduction
Data validation
Money representation
A PRACTICAL PLAN
Work through Calculate a cart total in cents with intent.
Translate the contract.Turn the requirements into a short checklist before editing your-solution.js.
Use the example as evidence.Predict the result for the supplied input, then add one boundary case such as an empty value, a limit, or unexpected input.
Review the implementation.Compare your choices against solution.js only after a real attempt.
EXERCISE FAQ
Before you move on.
What does “Calculate a cart total in cents” teach?
This intermediate JavaScript exercise focuses on Array reduction, Data validation, Money representation. Its requirements define the exact behavior to implement before you write code.
How should I validate this JavaScript solution?
Start with the displayed example input and expected output, then test a boundary case suggested by the requirements. Open your-solution.js and select Run code. The browser executes that file in an isolated worker against the visible test cases.
When should I open the reference solution?
Attempt Calculate a cart total in cents first. Then open the read-only solution file to compare the contract, edge-case handling, and implementation choices—not simply to copy the final code.
