const o = { name: 'Julie', greetBackwards: function() { const self = this; // thisを覚えておく function getReverseName() { let nameBackwards = ''; for(let i=self.name.length-1; i>=0; i--) { nameBackwards += self.name[i]; } return nameBackwards; } // getReverseNameの定義の終わり return `${getReverseName()} si eman ym ,olleH`; }, }; console.log(o.greetBackwards());