開始前建議可以先讀這篇卡斯伯的大補帖
https://wcc723.github.io/javascript/2017/06/29/es6-native-array/
初步練習目標 :
1.filter()
2.map()
3.sort()
4.reduce()
資料結構:
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 }
];
const people = ['Beck, Glenn', 'Becker, Carl', 'Beckett, Samuel', 'Beddoes, Mick', 'Beecher, Henry', 'Beethoven, Ludwig', 'Begin, Menachem', 'Belloc, Hilaire', 'Bellow, Saul', 'Benchley, Robert', 'Benenson, Peter', 'Ben-Gurion, David', 'Benjamin, Walter', 'Benn, Tony', 'Bennington, Chester', 'Benson, Leana', 'Bent, Silas', 'Bentsen, Lloyd', 'Berger, Ric', 'Bergman, Ingmar', 'Berio, Luciano', 'Berle, Milton', 'Berlin, Irving', 'Berne, Eric', 'Bernhard, Sandra', 'Berra, Yogi', 'Berry, Halle', 'Berry, Wendell', 'Bethea, Erin', 'Bevan, Aneurin', 'Bevel, Ken', 'Biden, Joseph', 'Bierce, Ambrose', 'Biko, Steve', 'Billings, Josh', 'Biondo, Frank', 'Birrell, Augustine', 'Black, Elk', 'Blair, Robert', 'Blair, Tony', 'Blake, William'];
const data = ['car', 'car', 'truck', 'truck', 'bike', 'walk', 'car', 'van', 'bike', 'walk', 'car', 'van', 'car', 'truck' ];
1.filter()
Filter the list of inventors for those who were born in the 1500's
目標:取得1500~1600年代出生的發明家。
const fifteen = inventors.filter(inventor => (inventor.year > 1500 && inventor.year < 1600))
console.table(fifteen)
2.map()
Give us an array of the inventors first and last names
目標:製作一筆資料,只要發明家的姓名。
const fullNames = inventors.map(inventor => `${inventor.first} ${inventor.last}`)
console.log(fullNames)
3.sort()
Sort the inventors by birthdate, oldest to youngest
目標:根據發明家的生日日期,由老到年輕排列。
const ordered = inventors.sort((a, b) => a.year - b.year);
console.table(ordered)
sort 可以 比較兩個丟進去的參數,總共需要判斷3種狀況,就能讓陣列由小到大排序
4.reduce()
How many years did all the inventors live?
目標:這些發明家總共活了多少年。
可以先用forEach來了解基礎的加總方法
let totalYears = 0
inventors.forEach(inventor => totalYears += inventor.passed-inventor.year)
console.log(totalYears)
用reduce()再做一次
const totalYears = inventors.reduce((total, inventor) => {
return total + (inventor.passed - inventor.year);
}, 0);
console.log(totalYears)
這幾個都是很常用到的陣列處理,
對於資料的整理會非常有幫助喔。
明天再繼續練習~