Javascript小型專案練習6-Array Cardio Day1 with JS(JS30-4)

這個小專案是來自https://javascript30.com/的教學，點擊進去輸入email後就可以進入課程~!此為第四篇學習紀錄!一樣先附上程式碼Javascript。
這篇比較特別一些，影片的目的是練習陣列的各種用法，內容也相對的簡單了很多，以下會依照題目附上程式碼。

Javascript

const inventors = [
  { first: 'Albert', last: 'Einstein', year: 1879, passed: 1955 },
  { first: 'Isaac', last: 'Newton', year: 1643, passed: 1727 },
  { first: 'Galileo', last: 'Galilei', year: 1564, passed: 1642 },
  { first: 'Marie', last: 'Curie', year: 1867, passed: 1934 },
  { first: 'Johannes', last: 'Kepler', year: 1571, passed: 1630 },
  { first: 'Nicolaus', last: 'Copernicus', year: 1473, passed: 1543 },
  { first: 'Max', last: 'Planck', year: 1858, passed: 1947 },
  { first: 'Katherine', last: 'Blodgett', year: 1898, passed: 1979 },
  { first: 'Ada', last: 'Lovelace', year: 1815, passed: 1852 },
  { first: 'Sarah E.', last: 'Goode', year: 1855, passed: 1905 },
  { first: 'Lise', last: 'Meitner', year: 1878, passed: 1968 },
  { first: 'Hanna', last: 'Hammarström', year: 1829, passed: 1909 }
]; 

1. Filter the list of inventors for those who were born in the 1500’s

const fifteen = inventors.filter(item => item.year >= 1500 && item.year < 1600);
console.table(fifteen) 

2. Give us an array of the inventors’ first and last names

const names = inventors.map(item => item.first + ' ' + item.last);
console.log(names) 

3. Sort the inventors by birthdate, oldest to youngest

const elder = inventors.sort((a, b) => a.year > b.year ? 1 : -1);
console.log(elder) 

4. How many years did all the inventors live?

const period = inventors.reduce((a, b) => a + (b.passed - b.year), 0)
console.log(period) 

5. Sort the inventors by years lived

const lasting = inventors.sort((a, b) => (a.passed - a.year) > (b.passed - b.year) ? 1 : -1);
console.table(lasting) 

6. Sum up the instances of each of these

const data = ['car', 'car', 'truck', 'truck', 'bike', 'walk', 'car', 'van', 'bike', 'walk', 'car', 'van', 'car', 'truck'];
const transportation = data.reduce((obj, item) => {
  if (!obj[item]) {
    obj[item] = 0
  }
  obj[item]++
  return obj
}, {})
console.log(transportation) 

學習重點

• 複習reduce的用法，起始點除了數值之外也可以採用空陣列或物件
• 複習sort的用法
• console.table也是不錯的表達方式