check if password is reused in typescript

To check if a password is reused, you need to use hashing and store the hashed value in a database. When a user enters a password, the entered password is hashed and compared to the hashed value stored in the database.

Here's an example of how to check if a password is reused using TypeScript and bcrypt.js, a popular hashing library:

index.ts
import bcrypt from 'bcrypt';

async function checkIfPasswordIsReused(password: string, hashedPassword: string): Promise<boolean> {
  const isPasswordMatch = await bcrypt.compare(password, hashedPassword);
  return isPasswordMatch;
}

// Usage
const enteredPassword = 'password123';
const hashedPasswordFromDb = '$2b$10$jMkpfE0XZYByN4.zGjKsruDOJgAcJVxiNQrGKkV7h8ZghAtu9jQ2a';
const isPasswordReused = await checkIfPasswordIsReused(enteredPassword, hashedPasswordFromDb);
console.log(isPasswordReused); // true or false
518 chars
13 lines

In the code above, checkIfPasswordIsReused is a function that takes in two parameters - the entered password and the hashed password from the database. bcrypt.compare is used to compare the entered password with the stored hashed password, returning a boolean value indicating whether the passwords match or not.

If the function returns true, then the entered password is the same as the password that was previously used and hashed.