Never use any — use unknown for truly unknown types | BeforeMerge Rules | BeforeMerge

Never use any — use unknown for truly unknown types | BeforeMerge Rules | BeforeMerge

Why This Matters

any is a type-system escape hatch. It disables ALL checking:

const x: any = "hello"
x.foo.bar.baz()  // No error! Crashes at runtime.

Good

function processInput(input: unknown) {
  if (typeof input === "string") {
    return input.toUpperCase()  // Safe — narrowed to string
  }
  throw new Error("Expected string")
}

Bad

function processInput(input: any) {
  return input.toUpperCase()  // Crashes if input isn't a string
}