Chapter 6. Purely functional state
We're going to investigate how to write purely functional programs that need to manipulate state, through the example of random number generation. Not particularly exciting in and of itself, but the idea is simple enough to make for a good introduction.
Generating random numbers using side effects
In bog-standard TypeScript/JavaScript, the universe of options available to you to generate a random number comprises
Math.random... and that's it.
> let randomNumber = Math.random();
undefined
> randomNumber
0.8158681035026218
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Do not use Math.random in situations that call for cryptographically secure random numbers (i.e. encryption, hashing
passwords, generating passwords, etc.). That is not its intended use and it is not suitable for such purposes. If you
have a need for secure randomness, start with Node's crypto module or the Web Crypto API.