function HFM(){  var souce = [];     function createNode(node){    var obj = {      weight:0,       parent:-1,      lchild:-1,      rchild:-1,      value:''    };         return Object.assign(obj,node);  }     this.addNode = function(node){    //添加單詞和頻率（權(quán)值）    souce.push(createNode(node));  }     this.createTree = function(){    //哈夫曼樹    var HuffNode = JSON.parse(JSON.stringify(souce));    var n = HuffNode.length;         var x1,x2; //兩個權(quán)值最小的索引    var m1,m2;     //兩個權(quán)值最小的值         for(var i = 0; i < n ; i++){      m1 = m2 = Infinity; //初始化為最大值      x1 = x2 = -1;             for(var j = 0; j < n+i; j++){ //尋找兩個權(quán)值最小，且父節(jié)點為-1的        var item = HuffNode[j];        if(item.weight < m1 && item.parent == -1){          m2 = m1;          x2 = x1;                     m1 = item.weight;          x1 = j;                   }else if(item.weight < m2 && item.parent == -1){          m2 = item.weight;;          x2 = j;        }      }             if(x1 != -1 && x2 != -1){        HuffNode[x1].parent = n + i; //更新父節(jié)點        HuffNode[x2].parent = n + i;                 //創(chuàng)建一個新的節(jié)點        HuffNode[n+i] = createNode({          weight:m1+m2,          lchild:x1,          rchild:x2        });      }                 }         return HuffNode;  };     this.getCode = function(){    //哈夫曼編碼    var n = souce.length;    var tree = this.createTree();    var codes = {};    for(var i = 0; i < n; i++){      var p = tree[i].parent;      var code = '';      var c = i;      while(p != -1){ //迭代前溯        if(tree[p].lchild == c){          code = 0 + code;        }else{          code = 1 + code;        }        c = p;        p = tree[p].parent;      }             codes[ tree[i].value ] = code;      console.log(tree[i].value , code);         }         return codes;  }     } var hfm = new HFM();hfm.addNode({  weight:5,  value:"a"});hfm.addNode({  weight:32,  value:"b"});hfm.addNode({  weight:18,  value:"c"});hfm.addNode({  weight:7,  value:"d"});hfm.addNode({  weight:25,  value:"e"});hfm.addNode({  weight:13,  value:"f"});console.log(hfm.getCode())