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
  }

// 循環(huán)遍歷當(dāng)前數(shù)組，當(dāng)前不在臨時數(shù)組的，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
  }

// 當(dāng)前數(shù)組的第i項在當(dāng)前數(shù)組第一次出現(xiàn)的位置不是i，當(dāng)前項即重復(fù)，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，找相鄰的項
  // 這個會改變原來數(shù)組的順序
  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
  }

// 優(yōu)化遍歷數(shù)組
  // 獲取沒重復(fù)的最右一值放入新數(shù)組
  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;
   })
  }