使用JavaScript实现二叉树的前序遍历，中序遍历，后序遍历
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<script>
function Node(value){
this.value = value;
this.left = null;
this.right = null;
}
var nodeA = new Node("a");
var nodeB = new Node("b");
var nodeC = new Node("c");
var nodeD = new Node("d");
var nodeE = new Node("e");
var nodeF = new Node("f");
var nodeG = new Node("g");
nodeA.left = nodeB;
nodeA.right = nodeC;
nodeB.left = nodeD;
nodeB.right = nodeE;
nodeC.left = nodeF;
nodeC.right = nodeG;
//前序遍历：先打印当前节点，再打印左边子树的节点，再打印右边子树的节点
//中序遍历：先打印左边子树的节点，再打印当前节点，再打印右边子树的节点
//后序遍历：先打印左边子树的节点，再打印右边子树的节点，再打印当前节点
//-------前序遍历---begin-----//
function DLR(root){//前序遍历
if(root == null) return;
console.log(root.value);//先输出
DLR(root.left);
DLR(root.right);
}
DLR(nodeA);//a b d e c f g
//-------前序遍历---end-----//
//-------中序遍历---begin-----//
function LDR(root){//前序遍历
if(root == null) return;
LDR(root.left);
console.log(root.value);
LDR(root.right);
}
LDR(nodeA);//d b e a f c g
//-------中序遍历---end-----//
//-------后序遍历---begin-----//
function LRD(root){//前序遍历
if(root == null) return;
LRD(root.left);
LRD(root.right);
console.log(root.value);
}
LRD(nodeA);//d e b f g c a
//-------后序遍历---end-----//
</script>
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