本文版權歸博客園和作者吳雙本人共同所有，轉載和爬蟲請注明原文鏈接博客園蝸牛 cnblogs.com\tdws .
首先提供一種獲取hashCode的方法，是一種比較受歡迎的方式，該方法參照了一位園友的文章，鏈接在尾部給出：
var djb2Code = function (str) { var hash = 5381; for (i = 0; i < str.length; i++) { char = str.charCodeAt(i); hash = ((hash << 5) + hash) + char; /* hash * 33 + c */ } return hash; }
接下來我們用js實現hashmap, hashmap是一種鍵值對的數據結構。意味着你可以通過key快速找到你所需要查找的值。我使用數組加上LinkedList來實現hashmap,這種方式也被稱為解決hashcode沖突的分離鏈接法。hashmap通常具備以下幾種方法：put,get,remove。put是寫入和修改數據，在put數據時，首先獲取key的hashcode,作為數組的索引。而數組索引對應的值則是一個linkedlist，並且linkedlist所存儲的節點值，同時包含着所需存儲的key和value。這樣以便解決當hashcode重復沖突時，在鏈表中根據key名稱來get查找值。 關於hashmap更多的原理，我推薦這篇文章 http://www.admin10000.com/document/3322.html
下面直接給出實現，其中使用到LinkedList數據結構的源碼，在我的這篇分享當中：http://www.cnblogs.com/tdws/p/6033209.html
1 var djb2Code = function (str) { 2 var hash = 5381; 3 for (i = 0; i < str.length; i++) { 4 char = str.charCodeAt(i); 5 hash = ((hash << 5) + hash) + char; /* hash * 33 + c */ 6 } 7 return hash; 8 } 9 10 11 12 function HashMap() { 13 var map = []; 14 var keyValPair = function (key, value) { 15 this.key = key; 16 this.value = value; 17 } 18 this.put = function (key, value) { 19 var position = djb2Code(key); 20 if (map[position] == undefined) { 21 map[position] = new LinkedList(); 22 } 23 map[position].append(new keyValPair(key, value)); 24 }, 25 this.get = function (key) { 26 var position = djb2Code(key); 27 if (map[position] != undefined) { 28 var current = map[position].getHead(); 29 while (current.next) { 30 if (current.element.key === key) { //嚴格判斷 31 return current.element.value; 32 } 33 current = current.next; 34 } 35 if (current.element.key === key) {//如果只有head節點，則不會進while. 還有尾節點，不會進while,這個判斷必不可少 36 return current.element.value; 37 } 38 } 39 return undefined; 40 }, 41 this.remove = function (key) { 42 var position = djb2Code(key); 43 if (map[position] != undefined) { 44 var current = map[position].getHead(); 45 while (current.next) { 46 if (current.element.key === key) { 47 map[position].remove(current.element); 48 if (map[position].isEmpty()) { 49 map[position] == undefined; 50 } 51 return true; 52 } 53 current = current.next; 54 } 55 if (current.element.key === key) { 56 map[position].remove(current.element); 57 if (map[position].isEmpty()) { 58 map[position] == undefined; 59 } 60 return true; 61 } 62 } 63 } 64 } 65 66 67 68 69 //鏈表 70 function LinkedList() { 71 var Node = function (element) { //新元素構造 72 this.element = element; 73 this.next = null; 74 }; 75 var length = 0; 76 var head = null; 77 78 this.append = function (element) { 79 var node = new Node(element); //構造新的元素節點 80 var current; 81 if (head === null) { //頭節點為空時 當前結點作為頭節點 82 head = node; 83 } else { 84 current = head; 85 while (current.next) { //遍歷，直到節點的next為null時停止循環，當前節點為尾節點 86 current = current.next; 87 } 88 current.next = node; //將尾節點指向新的元素，新元素作為尾節點 89 } 90 length++; //更新鏈表長度 91 }; 92 this.removeAt = function (position) { 93 if (position > -1 && position < length) { 94 var current = head; 95 var index = 0; 96 var previous; 97 if (position == 0) { 98 head = current.next; 99 } else { 100 while (index++ < position) { 101 previous = current; 102 current = current.next; 103 } 104 previous.next = current.next; 105 } 106 length--; 107 return current.element; 108 } else { 109 return null; 110 } 111 }; 112 this.insert = function (position, element) { 113 if (position > -1 && position <= length) { //校驗邊界 114 var node = new Node(element); 115 current = head; 116 var index = 0; 117 var previous; 118 if (position == 0) { //作為頭節點，將新節點的next指向原有的頭節點。 119 node.next = current; 120 head = node; //新節點賦值給頭節點 121 } else { 122 while (index++ < position) { 123 previous = current; 124 current = current.next; 125 } //遍歷結束得到當前position所在的current節點，和上一個節點 126 previous.next = node; //上一個節點的next指向新節點 新節點指向當前結點，可以參照上圖來看 127 node.next = current; 128 } 129 length++; 130 return true; 131 } else { 132 return false; 133 } 134 135 }; 136 this.toString = function () { 137 var current = head; 138 var string = ''; 139 while (current) { 140 string += ',' + current.element; 141 current = current.next; 142 } 143 return string; 144 }; 145 this.indexOf = function (element) { 146 var current = head; 147 var index = -1; 148 while (current) { 149 if (element === current.element) { //從頭節點開始遍歷 150 return index; 151 } 152 index++; 153 current = current.next; 154 } 155 return -1; 156 }; 157 this.getLength = function () { 158 return length; 159 }; 160 this.getHead = function () { 161 return head; 162 }; 163 this.isEmpty = function () { 164 return length == 0; 165 } 166 }
參考文章：js獲取hashcode ： http://www.cnblogs.com/pigtail/p/3342977.html
如果我的點滴分享對你有點滴幫助，歡迎點擊下方紅色按鈕，我將長期輸出分享。