Use Union Types
Don’t write overloads that differ by type in only one argument position:
1 2 3 4 5 6 | /* WRONG */interface Moment { utcOffset(): number; utcOffset(b: number): Moment; utcOffset(b: string): Moment;} |
Do use union types whenver possible:
1 2 3 4 5 | /* OK */interface Moment { utcOffset(): number; utcOffset(b: number|string): Moment;} |
Note that we didn’t make b optional here because the return types of the signatures differ.
Why: This is important for people who are “passing through” a value to your function:
1 2 3 4 5 6 7 | function fn(x: string): void;function fn(x: number): void;function fn(x: number|string) { // When written with separate overloads, incorrectly an error // When written with union types, correctly OK return moment().utcOffset(x);} |
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