JavaScript实现二叉树的先序、中序及后序遍历方法(2)

/**
 * Created by hp on 2016/12/22.
 */
var btn = document.getElementsByTagName('input'),
  preBtn = btn[0],
  inBtn = btn[1],
  postBtn = btn[2],
  treeRoot = document.getElementsByClassName('root')[0],
  divList = [],
  timer = null;
window.onload=function(){
  preBtn.onclick = function () {
    reset();
    preOrder(treeRoot);
    changeColor();
  }
  inBtn.onclick = function () {
    reset();
    inOrder(treeRoot);
    changeColor();
  }
  postBtn.onclick = function () {
    reset();
    postOrder(treeRoot);
    changeColor();
  }
}
/*先序遍历*/
function preOrder(node){
  if(!(node==null)){
    divList.push(node);
    preOrder(node.firstElementChild);
    preOrder(node.lastElementChild);
  }
}
/*中序遍历*/
function inOrder(node) {
  if (!(node == null)) {
    inOrder(node.firstElementChild);
    divList.push(node);
    inOrder(node.lastElementChild);
  }
}
/*后序遍历*/
function postOrder(node) {
  if (!(node == null)) {
    postOrder(node.firstElementChild);
    postOrder(node.lastElementChild);
    divList.push(node);
  }
}
/*颜色变化函数*/
function changeColor(){
  var i=0;
  divList[i].style.backgroundColor = 'blue';
  timer=setInterval(function(argument){
    i++;
    if(i<divList.length){
      divList[i-1].style.backgroundColor="#fff";
      divList[i].style.backgroundColor="blue";
    }
    else{
      divList[divList.length-1].style.backgroundColor="#fff";
    }
  },500)
}
function reset(){
  divList=[];
  clearInterval(timer);
  var divs=document.getElementsByTagName("div");
  for(var i=0;i<divs.length;i++){
    divs[i].style.backgroundColor="#fff";
  }
}