Careeroza

Why to Avoid any

any Spreads

any is contagious. Anything you read from an any value is also any, so one any can silently remove checking from a whole chain of code.

Example

Compare: with unknown the same mistake is caught at compile time (TS18046) instead of producing NaN in production.

function parseOrder(json: string): unknown {
  return JSON.parse(json);
}

const order = parseOrder('{"total": "1200"}');
const withTax = order.total * 1.18;
console.log(withTax);

Compiler output (tsc)

Line 6: error TS18046: 'order' is of type 'unknown'.

Better Alternatives to any

Instead of any, useWhen
unknownyou do not know the type yet and will check it
a union like string | numberthere are a few known possibilities
a specific object type or interfaceyou know the shape of the data
generics <T> (medium level)the function works with many types but keeps them connected
Record<string, unknown>any plain object with unknown values

Tip: Turn on the ESLint rule @typescript-eslint/no-explicit-any so nobody adds any by accident.