.gitignore

data.json

README.md

(Solved) Problem

Refer to: Using map and filter (not reduce) to get unique values of array (JavaScript).

1. I need to return all the years (for this example: [ 2019, 2018, 2017 ]) OR
2. I need to return the maximum and minimum year (for this example: 2019 and 2017);

Running

$ node ./index.js

Running (Using docker)

$ docker run --rm -v $(pwd):/app -w /app node node index.js

benchmark.js

// npm i microtime benchmark
var Benchmark = require('benchmark');
var suite = new Benchmark.Suite;
var data = require("./data.json")

suite.add("map+filter", function() {
  const result = data.map(record => {
    return record.period.split("-")[0]
  }).filter((elem, index, self) => {
    return index == self.indexOf(elem)
  })
})
.add("do+while", function() {
  if (data.length > 0) {
    let result = records.map(record => {
      return parseInt(record.period.split("-")[0])
    })

    let current
    let arr2 = []

    do {
      current = result.pop()
      if (arr2.indexOf(current) == -1) {
        arr2.push(current)
      }
    } while (result.length > 0)

    return arr2
  } else {
    return []
  }
})
.on("cycle", function(event) {
  console.log(String(event.target));
})
.on("complete", function() {
  console.log("Fastest is " + this.filter("fastest").map("name"));
})
.run({ "async": true });

index-using-loop.js

function getYears(records) {
  if (records.length > 0) {
    let result = records.map(record => {
      return parseInt(record.period.split("-")[0])
    })

    let current
    let arr2 = []

    do {
      current = result.pop()
      if (arr2.indexOf(current) == -1) {
        arr2.push(current)
      }
    } while (result.length > 0)

    return arr2
  } else {
    return []
  }
}

const data = [
  { "period": "2019-02-01", value: "10" },
  { "period": "2019-01-01", value: "1" },
  { "period": "2018-01-01", value: "2" },
  { "period": "2017-01-01", value: "3" },
]

console.log(getYears(data))

index.js

const data = [
  { "period": "2019-02-01", value: "10" },
  { "period": "2019-01-01", value: "1" },
  { "period": "2018-01-01", value: "2" },
  { "period": "2017-01-01", value: "3" },
]

const result = data.map(record => {
  return record.period.split("-")[0]
}).filter((elem, index, self) => {
  return index == self.indexOf(elem)
})

console.log(result)