Call a function if the parameters differ

changed.js

// Calls 'f' if the parameters are different from the last call.
// NOTE: Implement 'notEqual' yourself
const changed = f => {
  let lastParams = undefined, flag = false;
  return (...args) => {
    if (!flag || notEqual(lastParams, args)) {
      f(args);
      lastParams = args;
      flag = true
    }
  };
};