javascript - Can I Specify Parameter Type as One of Many Types Instead of Any Type in TypeScript?

Question

In a method declaration in TypeScript, the parameter could be of type array of strings, booleans, or numbers. Do I have to declare it as any[] or is there a way to limit the input type as on of these three types?

question from:https://stackoverflow.com/questions/12776625/can-i-specify-parameter-type-as-one-of-many-types-instead-of-any-type-in-typescr

Answer 1

Typescript 1.4 introduced Union Types so the answer now is yes, you can.

function myFunc(param: string[] | boolean[] | number[]): void;

Using other type than the ones specified will trigger a compile-time error.

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If you want an array of multiple specific types, you can use Union Types for that as well:

function myFunc(param: (string|boolean|number)[]): void;

Note that this is different from what OP asked for. These two examples have different meanings.