parseSalaryData.js

const fs = require('fs');
let rawData = fs.readFileSync('data.json');
let data = JSON.parse(rawData);
const convertToNumber = item => {
  item.workTimeRangeSum = Number(item.workTimeRangeSum.split(':').join('.').replace(/\.3/g, '.5'));
  return item;
}

const res = data.workDays
  .map(item => {
    item.dayOfWeek = new Date(item.day).getDay();
    return item;
  })
  .map(item => {
    if (item.dayOfWeek === 0) { // sunday
      item.rate = 150;
    } else if (item.dayOfWeek === 6) { // saturday
      item.rate = 120;
    } else {
      item.rate = 100;
    }
    return item;
  })
  .map(convertToNumber)
  .map(item => {
    return {
      workHours: item.workTimeRangeSum,
      rate: item.rate
    }
  })
  .filter(item => item.workHours)
  .reduce((acc, item) => {
    acc[`hours${item.rate}`] = acc[`hours${item.rate}`] + item.workHours;
    return acc;
  }, {
    'hours100': 0,
    'hours120': 0,
    'hours150': 0
  })

console.log(res);