JS Error Statements
Throw signals a failure and try/catch handles it. Put the validation close to the operation that requires valid input.
Where to run this
This example uses the JavaScript console playground. Select Run to execute it; the example does not run on this lesson page.
A practical example
function book(count) {
if (count < 1) throw new RangeError("Choose at least one place.");
return count;
}
try { book(0); } catch (error) { console.log(error.message); }
What happens
The invalid booking produces a readable validation message.