TypeScript Coding Guidelines

The goal of these guidelines is to make TypeScript's type system do real work: catching bugs before runtime, making contracts explicit, and eliminating the "it works if you pass the right thing" class of errors. Follow them automatically whenever working in TypeScript — don't wait for the user to ask.

No any

any disables the type checker for that value and everything that touches it. Use unknown when you don't know the type yet — it forces you to narrow before using the value, which is the point.

// ❌ — silences the type checker; errors hide until runtime
function parse(data: any): any {
    return data.value; // no error even if data has no .value
}