[JS] Day4 - Array Cardio Day1

17357 ワード


[JS] Day4 - Array Cardio Day1


🎯 機能要件

  • map()、reduce()、filter()、sort()などの配列方法を使用します.
  • 🚀 学識


    よく使う方法なので難しくはありませんが、sortを見るたびに混同してしまいます.
    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 = [
          'Bernhard, Sandra', 'Bethea, Erin', 'Becker, Carl', 'Bentsen, Lloyd', 'Beckett, Samuel', 'Blake, William', 'Berger, Ric', 'Beddoes, Mick', 'Beethoven, Ludwig',
          'Belloc, Hilaire', 'Begin, Menachem', 'Bellow, Saul', 'Benchley, Robert', 'Blair, Robert', 'Benenson, Peter', 'Benjamin, Walter', 'Berlin, Irving',
          'Benn, Tony', 'Benson, Leana', 'Bent, Silas', 'Berle, Milton', 'Berry, Halle', 'Biko, Steve', 'Beck, Glenn', 'Bergman, Ingmar', 'Black, Elk', 'Berio, Luciano',
          'Berne, Eric', 'Berra, Yogi', 'Berry, Wendell', 'Bevan, Aneurin', 'Ben-Gurion, David', 'Bevel, Ken', 'Biden, Joseph', 'Bennington, Chester', 'Bierce, Ambrose',
          'Billings, Josh', 'Birrell, Augustine', 'Blair, Tony', 'Beecher, Henry', 'Biondo, Frank'
        ];
        // 7. sort Exercise
        // Sort the people alphabetically by last name
        people.sort((a,b) => a.split(', ')[0] > b.split(', ')[0] ? 1 : -1);
    
        // 5. Sort the inventors by years lived
        inventors.sort((a, b) => (b.passed - b.year) - (a.passed - a.year));
    
        // 3. Sort the inventors by birthdate, oldest to youngest
        inventors.sort((a,b) => b.year - a.year);
    const arr = [4, 2, 1, 10];
    //arr.sort([compareFunction])
    arr.sort((a, b) =>{
    
        console.log(`${a} - ${b}`);
        return a - b;
    });
    
    // [ 1, 2, 4, 10 ]
    
    
    compareFunctionが指定されている場合、配列要素はcompare関数の戻り値に基づいてソートされます.
    compareFunction(a,b)の戻り値が負の場合、a b順(反転)になります.
    Function(a,b)の戻り値を比較してbの正の方向をaより優先する方向を並べ替える(そのまま)
    x)[4, 2, 1, 10]開始時、a=2 b=4、前の値b、後の値a.