js史上最全的数组去重方法

简介：堪称史上最全数组去重

//一、set(es6新增)
/* function fn(arr){
    return Array.from(new Set(arr));
}
var arr=[11,11,22,22,22,33,33,44,44,44,55,55,"a","b","c","a","b","c"];
console.log(fn(arr)); */
//二、splice
/* function fn(arr){
    for(var i=0;i<arr.length;i++){
        for(var j=i+1;j<arr.length;j++){
            if(arr[i]==arr[j]){
                arr.splice(j,1);
                j--;
            }
        }
    }
    return arr;
}
arr=[11,11,22,22,22,33,33,44,44,44,55,55,"a","b","c","a","b","c"];
console.log(fn(arr)) */
//三、indexOf
/* function fn(){
    if(!Array.isArray(arr)){
        console.log('type error!');
        return;
    }
    var array=[];
    for(var i=0;i<arr.length;i++){
        if(array.indexOf(arr[i]===-1)){
            array.push(arr[i]);//把array数组中没有的数据放进array中
        }
    }
} */
//四、sort()
/* function fn(arr){
    if(!Array.isArray(arr)){
        console.log('type error!')
        return;
    }
    arr=arr.sort();//先排序
    var array=[arr[0]];
    for(var i=1;i<arr.length;i++){
        if(arr[i]!==arr[i-1]){
            array.push(arr[i]);//把排序好的数组里的元素与后一个元素进行对比，不一样的放入新数组
        }
    }
    return array;
}
var arr=[11,11,22,22,22,33,33,44,44,44,55,55,"a","b","c","a","b","c"];
console.log(fn(arr));  */
//五、对象属性不能相同
/* function fn(arr){
    if(!Array.isArray(arr)){
        console.log('type error!');
        return;
    }
    var array=[];
    var obj={};
    for(var i=0;i<arr.length;i++){
        if(!obj[arr[i]]){
            array.push(arr[i]);
            obj[arr[i]]=1;
        }else{
            obj[arr[i]]++;
        }
    }
    return array;
}
var arr=[11,11,22,22,22,33,33,44,44,44,55,55,"a","b","c","a","b","c"];
console.log(fn(arr)); */
//六、includes
/* function fn(arr){
    if(!Array.isArray(arr)){
        console.log('type error!');
        return;
    }
    var array=[];
    for(var i=0;i<arr.length;i++){
        if(!array.includes(arr[i])){
            array.push(arr[i]);
        }
    }
    return array;
}
var arr=[11,11,22,22,22,33,33,44,44,44,55,55,"a","b","c","a","b","c"];
console.log(fn(arr)); */
//七、hasOwnProperty
/* function fn(arr){
    var obj={};
    return arr.filter(function(item,index,arr){
        return obj.hasOwnProperty(typeof item+item)?false:(obj[typeof item+item]=true)
    })
}
var arr=[11,11,22,22,22,33,33,44,44,44,55,55,"a","b","c","a","b","c"];
console.log(fn(arr)); */
//八、filter
/* function fn(arr){
    return arr.filter(function(item,index,arr){
        return arr.indexOf(item,0)===index;
    });
}
var arr=[11,11,22,22,22,33,33,44,44,44,55,55,"a","b","c","a","b","c"];
console.log(fn(arr)); */
//九、不能给字符串去重
/* function fn(arr){
    var array=arr;
    var len=array.length;
    array.sort(function(a,b){
        return a-b;

    })
    function loop(index){
        if(index>=1){
            if(array[index]===array[index-1]){
                array.splice(index,1);

            }
            loop(index-1);
        }
    }
    loop(len-1);
    return array;
}
var arr=[11,11,22,22,22,33,33,44,44,44,55,55,"a","b","c","a","b","c"];
console.log(fn(arr)); */
//十、map
/* function fn(){
    let map=new Map();
    let array=new Array();
    for(let i=0;i<arr.length;i++){
        if(map.has(arr[i])){
            map.set(arr[i],true);
       }else{
           map.set(arr[i],false);
           array .push(arr[i]);
       }
    }
    return array;
}
var arr=[11,11,22,22,22,33,33,44,44,44,55,55,"a","b","c","a","b","c"];
console.log(fn(arr)); */
//十一、reduce+includes
/* function fn(arr){
    return arr.reduce((prev,cur)=>prev.includes(cur)?prev:[...prev,cur],[])
}
var arr=[11,11,22,22,22,33,33,44,44,44,55,55,"a","b","c","a","b","c"];
console.log(fn(arr)); */
//十二、...new set(arr)
let arr1 = [1, 2, 6, 54, 3, 6, 8, 9, 23, 55];
let arr2 = [...new Set(arr1)]
console.log(arr2);