Array.prototype.unique1 = function () {
   var r = {},
    temp = []
   for (var i = 0; i < this.length; i++) {
    if (!r[this[i]]) {
     r[this[i]] = 1
     temp.push(this[i])
    }
   }
   return temp
  }

Array.prototype.unique2 = function () {
   for (var i = 0; i < this.length; i++) {
    for (var j = i + 1; j < this.length; j++) {
     if (this[i] === this[j]) {
      this.splice(j, 1)
      j--
     }
    }
   }
   return this
  }

// 循环遍历当前数组，当前不在临时数组的，push
  Array.prototype.unique3 = function () {
   var temp = []
   for (var i = 0; i < this.length; i++) {
    if (temp.indexOf(this[i]) === -1) temp.push(this[i])
   }
   return temp
  }

// 当前数组的第i项在当前数组第一次出现的位置不是i，当前项即重复，反之
  Array.prototype.unique4 = function () {
   var temp = [this[0]]
   for (var i = 1; i < this.length; i++) {
    if (this.indexOf(this[i]) === i) temp.push(this[i])
   }
   return temp
  }

// 先排序，找相邻的项
  // 这个会改变原来数组的顺序
  Array.prototype.unique5 = function () {
   var tempArr = this.sort(),
    temp = [tempArr[0]]
   for (var i = 1; i < tempArr.length; i++) {
    if (tempArr[i] !== temp[temp.length - 1]) temp.push(tempArr[i])
   }
   return temp
  }

// 优化遍历数组
  // 获取没重复的最右一值放入新数组
  Array.prototype.unique6 = function () {
   var temp = []
   for (var i = 0; i < this.length; i++) {
    for (j = i + 1; j < this.length; j++) {
     if (this[i] === this[j]) {
      i++;
      j = i;
     }
    }
    temp.push(this[i])
   }
   return temp
  }

  Array.prototype.unique7 = function () {
   var temp = new Set(this)
   return [...temp]
  }

  Array.prototype.unique8 = function () {
   return this.filter(function (ele, index, self) {
    return self.indexOf(ele) === index;
   })
  }