Type Inference
Type Inference
π¨βπΌ Great detective work! You found and fixed the bug.
When you added
: number as the return type, TypeScript immediately flagged the
string return as an error. This is why explicit return types can be valuable:// Without explicit return type - no error, bug ships to production
function divide(a: number, b: number) {
if (b === 0) return 'error' // π±
return a / b
}
// With explicit return type - caught at compile time!
function divide(a: number, b: number): number {
if (b === 0) return 'error' // β Type 'string' is not assignable to 'number'
return a / b
}
π¦ The rule of thumb:
- Let inference work for simple, obvious functions
- Add explicit types for public APIs and when you want to catch this class of bugs early
