1. 목표

Array.prototype.some()

Array.prototype.every()

Array.prototype.find()

Array.prototype.findIndex()

Array.prototype.splice(start,deleteCount,item1,item2, ...)

Array.prototype.slice()

를 사용할 수 있다.

2.정리

## Array Cardio Day 2
      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 },
      ];

      // 1. Some and Every Checks
      // Array.prototype.some() // is at least one person 19 or older?
      // 하나라도 true면 true
      const haveAdult = people.some((person) => {
        const year = new Date().getFullYear();
        return year - person.year >= 19;
      });
      console.log(haveAdult); // true
      // Array.prototype.every() // is everyone 19 or older?
      // 전부다 true인지 확인
      const isAllAdult = people.every((person) => {
        return new Date().getFullYear() - person.year >= 19;
      });
      console.log(isAllAdult); // false

      // 2. Array.prototype.find()
      // Find is like filter, but instead returns just the one you are looking for
      // filter와 비슷하지만, 맨 처음 찾는 요소만 리턴해준다.
      // find the comment with the ID of 823423
      const comment = comments.find((comment) => comment.id === 823423);
      console.log(comment); // {text: 'Super good', id: 823423}

      // 3. Array.prototype.findIndex()
      // Find the comment with this ID
      // 찾는 요소의 index를 리턴
      // delete the comment with the ID of 823423
      const index = comments.findIndex((comment) => comment.id === 823423);

      // Array.prototype.splice(start,deleteCount,item1,item2, ...) 시작인덱스, 삭제할 갯수, 추가할 item들
      // 배열요소 삭제
      const deleted = comments.splice(index, 1); // index부터, 1개를 삭제
      // 배열요소 추가
      comments.splice(index, 0, ...deleted); // index부터 0개삭제, 요소추가

      // Array.prototype.slice() and ES6 spread operator
      // 배열요소 삭제 2
      const newComments = [
        ...comments.slice(0, index),
        ...comments.slice(index + 1),
      ];
      console.log(newComments);
      /*
        [
          0: {text: 'Love this!', id: 523423}
          1: {text: 'You are the best', id: 2039842}
          2: {text: 'Ramen is my fav food ever', id: 123523}
          3: {text: 'Nice Nice Nice!', id: 542328}
        ]
      */