Alex老師教學

練習用資料

const people = [
    { name: 'Wes', year: 1988 },
    { name: 'Kait', year: 1986 },
    { name: 'Irv', year: 1970 },
    { name: 'Lux', year: 2015 }
   ];

const comments = [
    { text: 'Love this!', id: 523423 },
    { text: 'Super good', id: 823423 },
    { text: 'You are the best', id: 2039842 },
    { text: 'Ramen is my fav food ever', id: 123523 },
    { text: 'Nice Nice Nice!', id: 542328 }
   ];

Q1

	// Array.prototype.some() 
   // 可用在搜尋購物車標籤、檢查產品內包含的特定項目、陣列比較
   // is at least one person 19 or older?
   //    至少有一個人是19歲以上？
   let ans = people.some(item => {
       return new Date().getUTCFullYear() - item.year >= 19;
   });
   console.log(ans); //true

Q2

// Array.prototype.every() 
   // is everyone 19 or older?
   //全部人都是19歲以上？
   let ans2 = people.every(item => {
       return new Date().getUTCFullYear() - item.year >= 19;
   });
   console.log(ans2); //false

Q3

// Array.prototype.find() 
   // 找出第一筆符合的物件本身，有多筆相同資料也只呈現第一筆   
   // Find is like filter, but instead returns just the one you are looking for
   // find the comment with the ID of 823423
   let ans3 = comments.find(item => {
       return item.id === 823423;
   })
console.log(ans3); //{text: "Super good1", id: 823423}

Q4

// Array.prototype.findIndex()  
   //找出陣列中第一筆符合的元素並回傳其位置序列，找不到會回傳-1
   // Find the comment with this ID
   let ans4 = comments.findIndex(item => {
       return item.id === 823423;
   })
   console.log(ans4); //1 ，陣列從0開始

Q5-使用splice

	// delete the comment with the ID of 823423
   //splice(刪除的位置,刪除的數量,新加入的內容)
   //splice(0,0,xxx) = 單純加入xxx內容
   const ans5 = comments.splice(ans4, 1);
   console.log(ans5, comments);

 //不動原始資料的做法
	const ans8 = [...comments].splice(ans4, 1);
   console.log(ans8, comments);

Q5-使用slice

// delete the comment with the ID of 823423
   const ans6 = comments.slice(0, ans4);
   const ans7 = comments.slice(ans4 + 1);
   console.log([...ans6, ...ans7], comments);

連結