04-map-filter-sort-reduce.js

04-map-filter-sort-reduce.js

const R  = require('ramda')

const products = [...]

// R.map
const productNameProp = R.prop('product_name')
const getProductNameList = R.map(productNameProp)
const mapResult = getProductNameList(products)
// console.log(mapResult)

// R.filter
const qtyMoreThan = (value) => R.propSatisfies(R.gt(R.__, value), 'quantity')
const filterQtyMoreThan = (value) => R.filter(qtyMoreThan(value))
const filterQtyMoreThan250 = filterQtyMoreThan(250)
const filterQtyMoreThan300 = filterQtyMoreThan(300)
const filterResult = filterQtyMoreThan250(products)
// const filterResult = filterQtyMoreThan300(products)
// console.log(filterResult)

// R.sort
const quantityProp = R.prop('quantity')
const sort = R.curry((isAscending, prop) => isAscending ? R.sort(R.ascend(prop)) : R.sort(R.descend(prop)))
const sortAsc = sort(true)
const sortDesc = sort(false)
const sortQuantityAsc = sortAsc(quantityProp)
const sortQuantityDesc = sortDesc(quantityProp)
// const sortResult = sortQuantityAsc(products)
const sortResult = sortQuantityDesc(products)
// console.log(sortResult)

// R.reduce
const concatProductName = (names, name) => `${names}${names && '\n'}${name}`
const reduceProductName = R.reduce(concatProductName, '')

const result = R.pipe(
  filterQtyMoreThan(100),
  sortQuantityDesc,
  getProductNameList,
  reduceProductName
)(products)

console.log(result)