memoize.js

const memoize = require('memoize')

const date = memoize(function(seed, cb) {
  setTimeout(function() {
    cb(null, Date.now(), seed)
  }, 100)
})

date({ name: "John", username: "codejockie" }, function(err, d1, seed1) { // given a set of arguments
  console.log(d1, seed1) // 1304606051552
  date({ name: "John", username: "codejocki" }, function(err, d2, seed2) { // same arguments
    console.log(d2, seed2) // 1304606051552  cached! same results
    date({ name: "Kennedy", sex: "Male" }, function(err, d3, seed3) { // we changed the arguments
      console.log(d3, seed3) // 1304606051652  so it's different
    })
  })
})

function fakeApi(param, cb) {
  setTimeout(function() {
    cb(null, param)
  }, 100)
}

const memoized = memoize(function(config, cb) {
  fakeApi(config, (err, res) => {
    cb(err, res)
  })
})

memoized({ name: "John", username: "codejockie" }, function(err, d1) {
  console.log(d1)
  date({ name: "John", username: "codejocki" }, function(err, d2) {
    console.log(d2)
    date({ name: "Kennedy", sex: "Male" }, function(err, d3) {
      console.log(d3)
    })
  })
})