对象和数组

let obj = {
    name:"张三",
    age:18,
    like:"音乐，电影"
};
let ary = ["chinese",80,"math",90,"english",85];


//数组转对象：
function ao(ary){
    let obj1 = {};
    for(let i=0;i<ary.length;i++){
        let cur = ary[i];
        let curn = ary[i+1];
        if(i%2===0 && (i+1)%2===1){
            obj1[cur] = curn;
        }
    }
    return obj1;
}

21 console.log(ao(ary));

如果数组的格式是[{name:'abc',age:18},{name:'efg',age:20},{name:'hij',age:21}] 
遍历数组的每一项，拿出每一项的name作为obj1的key，拿出每一项的age作为value，就是将数组每一项改造为key:value的形式存入对象

//对象转数组：
function oa(obj){
    let ary1 = [];
    for(let key in obj){
        if(obj.hasOwnProperty(key)){
            ary1.push(key);//属性名
            ary1.push(obj[key]);//属性值
        }
    }
    return ary1;
}
console.log(oa(obj));

//数组克隆：
let ary1 = ary.concat();
ary1.pop();
console.log(ary1,ary);

//对象克隆：
let obj1 = {};
for(let key in obj){
    if(obj.hasOwnProperty(key)){
        obj1[key] = obj[key];
    }
}
obj1.name="李四";
console.log(obj1,obj);



console.log(ao(oa(ao(ary))));

 

深度克隆

function deepClone(obj){
  let newObj = Array.isArray(obj) ? [] : {};
  if(obj && typeof obj === 'object'){
     for(let key in obj){
        if(obj.hasOwnProperty(key)){
            newObj[key] = (obj && typeof obj[key] === 'object') ? deepClone(obj[key]) : obj[key];
        }
    }   
  }
  return newObj;    
}

 

jq的each方法

    var obj = {
        name:'asdf',
        age:12,
        sex:0
    };
    var ary = [12,23,34,45];
    //jq遍历数组两种方法结果一样
    $.each(ary,function(index,item){
        console.log(index,item)
    })
    $(ary).each(function(index,item){
        console.log(index,item)
    })
    //jq遍历对象只能用这种方法
    $.each(obj,function(key,value){
        console.log(key,value)
    })

 

数组去重

let arr = [1, 2, 2, 3, 4, 4, 5];

let uniqueArr1 = [...new Set(arr)];

let uniqueArr2 = [...new Map(arr.map(item => [item, item])).values()];

let uniqueArr3 = arr.filter((item, index) => arr.indexOf(item) === index);

let uniqueArr4 = arr.filter((item, index) => !arr.includes(item, index + 1))

let uniqueArr5 = arr.reduce((acc, current) => {
  if (acc.indexOf(current) < 0) {
    acc.push(current);
  }
  return acc;
}, []);
console.log(uniqueArr1)// 输出: [1, 2, 3, 4, 5]