Array.prototype.distinct = function(){
  var arr = this,
    result = [],
    i,
    j,
    len = arr.length;
  for(i = 0; i < len; i++){
    for(j = i + 1; j < len; j++){
      if(arr[i] === arr[j]){
        j = ++i;
      }
    }
    result.push(arr[i]);
  }
  return result;
}
var arra = [1,2,3,4,4,1,1,2,1,1,1];
arra.distinct();       //返回[3,4,2,1]

Array.prototype.distinct = function (){
  var arr = this,
    i,
    j,
    len = arr.length;
  for(i = 0; i < len; i++){
    for(j = i + 1; j < len; j++){
      if(arr[i] == arr[j]){
        arr.splice(j,1);
        len--;
        j--;
      }
    }
  }
  return arr;
};
var a = [1,2,3,4,5,6,5,3,2,4,56,4,1,2,1,1,1,1,1,1,];
var b = a.distinct();
console.log(b.toString()); //1,2,3,4,5,6,56

Array.prototype.distinct = function (){
  var arr = this,
    i,
    obj = {},
    result = [],
    len = arr.length;
  for(i = 0; i< arr.length; i++){
    if(!obj[arr[i]]){  //如果能查找到，证明数组元素重复了
      obj[arr[i]] = 1;
      result.push(arr[i]);
    }
  }
  return result;
};
var a = [1,2,3,4,5,6,5,3,2,4,56,4,1,2,1,1,1,1,1,1,];
var b = a.distinct();
console.log(b.toString()); //1,2,3,4,5,6,56

Array.prototype.distinct = function (){
  var arr = this,
    len = arr.length;
  arr.sort(function(a,b){    //对数组进行排序才能方便比较
    return a - b;
  })
  function loop(index){
    if(index >= 1){
      if(arr[index] === arr[index-1]){
        arr.splice(index,1);
      }
      loop(index - 1);  //递归loop函数进行去重
    }
  }
  loop(len-1);
  return arr;
};
var a = [1,2,3,4,5,6,5,3,2,4,56,4,1,2,1,1,1,1,1,1,56,45,56];
var b = a.distinct();
console.log(b.toString());    //1,2,3,4,5,6,45,56

Array.prototype.distinct = function (){
  var arr = this,
    result = [],
    len = arr.length;
  arr.forEach(function(v, i ,arr){    //这里利用map，filter方法也可以实现
    var bool = arr.indexOf(v,i+1);    //从传入参数的下一个索引值开始寻找是否存在重复
    if(bool === -1){
      result.push(v);
    }
  })
  return result;
};
var a = [1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,3,3,3,3,3,3,3,2,3,3,2,2,1,23,1,23,2,3,2,3,2,3];
var b = a.distinct();
console.log(b.toString());  //1,23,2,3

function dedupe(array){
  return Array.from(new Set(array));
}
dedupe([1,1,2,3]) //[1,2,3]

let arr = [1,2,3,3];
let resultarr = [...new Set(arr)];  
console.log(resultarr); //[1,2,3]