In TypeScript you can use union types to describe values that can be of more than one type. It therefore allows to avoid using any. Define union types with the | character to separate the different possible types.
For example, let’s say a function definition uses parameters that describe values that can be either strings or numbers. Instead of this:
function add(v1: any, v2: any) {
let value1 = typeof v1 === "string" ? +v1 : v1;
let value2 = typeof v2 === "string" ? +v2 : v2;
console.log(value1 + value2);
}
add(23, "32"); // 55
add(23, true); // No error when passing non-string or number value
You can do this:
function add(v1: number | string, v2: number | string) {
let value1 = typeof v1 === "string" ? +v1 : v1;
let value2 = typeof v2 === "string" ? +v2 : v2;
console.log(value1 + value2);
}
add(23, "32"); // 55
add(23, true); // Error when passing non-string or number value
Join our DigitalOcean community of over a million developers for free! Get help and share knowledge in our Questions & Answers section, find tutorials and tools that will help you grow as a developer and scale your project or business, and subscribe to topics of interest.
Sign up