Why You Should Avoid Using any (and What to Do Instead)

any is a special TypeScript type that tells the compiler:

"Trust me, I know what I'm doing."

When you use any, TypeScript turns off type checking for that variable — which defeats the purpose of using TypeScript in the first place.

let data: any = "hello";
data.toFixed(); // No error, but will crash at runtime

Why Overusing any is a Problem

The biggest benefit of TypeScript is catching bugs before they happen. any disables that:

function handleUser(user: any) {
  // You might assume this is safe, but it's not
  console.log(user.name.toUpperCase()); 
  // It will crash if `user.name` is undefined or not a string
}

Plus, you miss out on one of the best developer experience features of TypeScript:

Helpful autocompletion and suggestions from your IDE!

const user: any = getUser();
user. // <- No suggestions 😭. You're flying blind.

What to Use Instead

Use unknown over any

If you truly don’t know the type yet, use unknown. It forces you to do checks before using the value:

function handle(data: unknown) {
  if (typeof data === "string") {
    console.log(data.toUpperCase());
  }
}

Use Partial, Pick, etc. for Flexibility

TypeScript utility types let you write more flexible types without giving up safety:

type UserUpdate = Partial<User>;

More can be found in the Utility Types section.

Ending notes

Rule of Thumb:

If you’re using any, ask yourself: “What am I losing in type safety by doing this?”