ES6 'use strict'; var family = [ {'name':'Namihei', 'age': 54}, {'name':'Masuo', 'age': 28}, {'name':'Katsuo', 'age': 11}, {'name':'Tarao', 'age': 3} ]; var family1 = family.filter(function(person) { return person.age < 30; }); var family2…

> var a = [1, 2, 3] undefined > a [1, 2, 3] > a.reverse(); [3, 2, 1] > a [3, 2, 1] > a.slice().reverse(); [1, 2, 3] > a [3, 2, 1] a.reverse() で破壊的 a.slice().reverse() で非破壊的 参考 Reverse array in Javascript without altering the ori…