stateless vs stateful example

fp_vs_oop.js

// stateful vs stateless
let x = 1;
const stateful = () => x = x + 1;
stateful(); // x = 2
stateful(); // x = 3

const stateless = (x) => x + 1;
stateless(x); // x = 4
stateless(x); // x = 4

// imperative vs declarative
// https://dzone.com/articles/imperative-vs-declarative-javascript

const isSubarray = (needle=[], haystack=[]) => {
  for (let i=0; i < needle.length; i++) {
    if (haystack.indexOf(needle[i]) === -1) {
        return false;
    }
  }
  return true;
}

const isSubarray = (needle=[], haystack=[]) => {
  return needle.every(el => haystack.includes(el));
}

// functions as first-class citizens

const withLossLimitsCheck = (callback: () => any, errorHandler: () => any) => {
  const checkLimitResult = Limits.RollingLimits.checkLimit(
    ...
  );

  if (!checkLimitResult) return errorHandler();

  return callback();
}

withLossLimitsCheck(() =>
  Banking.FiatApi.processDeposit({
    ...
  },
  Banking.FiatApi.handleError({
    ...
  })
);