What does the following conditional type produce for T = string | number? type StringOnly = T extends string ? T : never; type Result = StringOnly;

Question

TypeScript Professional — Hard

What does the following conditional type produce for T = string | number? type StringOnly = T extends string ? T : never; type Result = StringOnly;

Accepted Answer

The conditional type StringOnly filters the union type T = string | number to only include strings. Since 'number extends string' evaluates to never, the Result type is string.