数组去重

两个数组除去id相同的

   const arr1 = [
        {id:1,name:'a'},
        {id:2,name:'abc'},
        {id:3,name:'abbb'}, 
        {id:4,name:'abxxx'}, 
        {id:5,name:'xyz'},
        {id:6,name:'abcdef'},
        {id:7,name:'abzzzz'}
      ];
    const arr2 = [
        {id:1,name:'a'},
        {id:5,name:'xyz'},
        {id:7,name:'abzzzz'}
      ];
  let result = arr1.filter(item1 => arr2.every(item2 => item2.id !== item1.id))
  console.log(result)

输出结果

image.png

单个数组去重，形成新的数组

方法1

  let array = [1, 1, 1, 1, 2, 3, 4, 4, 5, 3, undefined, undefined, null, null, Object, Object];
  let set = Array.from(new Set(array));
  console.log(set);

输出结果

image.png

方法2

  let arr = [1, 2, 2, 3, 4, 5, 5, 6, 7, 7, 8, 8, 0, 8, 6, 3, 4, 56, 2, undefined, undefined, null, null, Object, Object];
  let arr2 = arr.filter((x, index, self) => self.indexOf(x) === index)
  console.log(arr2)

输出结果

image.png

数组内去除相同id的对象
方法1:

let person = [
     {id: 0, name: "小明"},
     {id: 1, name: "小张"},
     {id: 2, name: "小李"},
     {id: 3, name: "小孙"},
     {id: 1, name: "小周"},
     {id: 2, name: "小陈"}, 
    
];

let obj = {};

let arr = person.reduce((cur,next) => {
    obj[next.id] ? "" : obj[next.id] = true && cur.push(next);
    return cur;
},[]) //设置cur默认类型为数组，并且初始值为空的数组
console.log(arr);

输出结果

image.png

方法2:

let person = [
     {id: 0, name: "小明", testId: 1},
     {id: 1, name: "小张", testId: 2},
     {id: 2, name: "小李", testId: 3},
     {id: 3, name: "小孙", testId: 4},
     {id: 1, name: "小周", testId: 1},
     {id: 2, name: "小陈", testId: 1}, 
    
];

function filterSameIndex(arr, index) {
    // arr是数组,index是要过滤的目标
    let array = arr
    array.forEach(c => {
        const res = arr.filter(i => i[index] !== c[index])
        arr = [...res, c]
    })
    console.log(arr)
    return arr
}

filterSameIndex(person, 'testId')

输出结果

image.png

两个数组合并,有相同键的替换,不同则添加

let arr = [
    { key: 1, name: '1-1' },
    { key: 2, name: '1-2' },
    { key: 3, name: '1-3' },
    { key: 4, name: '1-4' },
]
let arr1 = [
    { key: 1, name: '2-1' },
    { key: 3, name: '2-3' },
    { key: 5, name: '2-5' },
]
let arr2 = []
let obj = {};
arr2 = [...arr, ...arr1].reduce((cur, next) => {
    if (obj[next.key]) {
        let index = cur.findIndex(item => item.key === obj[next.key])
        cur.splice(index, 1, next)
    } else {
        // 因为对象是储存的键值对，
        // 所以对象obj的键arr[i]必须对应一个值，这个值是什么不重要，但别是undefined，因为这样你就不容易判断对象里面有没有这个键。
        obj[next.key] = next.name && cur.push(next)
    }
    return cur;
}, []) //设置cur默认类型为数组，并且初始值为空的数组

console.log('arr2', arr2)

输出结果:

image.png