基于JavaScript实现树形下拉框

[{ id: 19, pid: 0, name: 'nodejs' },{ id: 20, pid: 19, name: 'express' },{ id: 21, pid: 19, name: 'mongodb' },{ id: 60, pid: 20, name: 'ejs' },{ id: 59, pid: 0, name: '前端开发' },{ id: 70, pid: 59, name: 'javascript' },{ id: 71, pid: 59, name: 'css' },{ id: 72, pid: 59, name: 'html' },{ id: 73, pid: 59, name: 'bootstrap' },{ id: 61, pid: 0, name: '视觉设计' },{ id: 63, pid: 61, name: '网页设计' },]

[{ id: 19, pid: 0, name: 'nodejs', children:[   { id: 20, pid: 19, name: 'express',children:[{ id: 60, pid: 20, name: 'ejs' }]},   { id: 21, pid: 19, name: 'mongodb' }   ]},{ id: 59, pid: 0, name: '前端开发', children:[  { id: 70, pid: 59, name: 'javascript' },  { id: 71, pid: 59, name: 'css' },  { id: 72, pid: 59, name: 'html' },  { id: 73, pid: 59, name: 'bootstrap' }   ]},{ id: 61, pid: 0, name: '视觉设计',children:[{ id: 63, pid: 61, name: '网页设计' }]},]

//list 转成树形jsonfunction listToTree(list,pid) {var ret = [];//一个存放结果的临时数组for(var i in list) {if(list[i].pid == pid) {//如果当前项的父id等于要查找的父id，进行递归 list[i].children = listToTree(list, list[i].id); ret.push(list[i]);//把当前项保存到临时数组中}}return ret;//递归结束后返回结果}var tree=listToTree(list,0);//调用函数，传入要转换的list数组，和树中顶级元素的pidconsole.log(tree);

//在网页中添加下拉框容器<select id="selectbox" name=""></select>//js脚本，递归生成//获取容器对象var selectbox=document.getElementById("selectbox");//生成树下拉菜单var j="-";//前缀符号，用于显示父子关系，这里可以使用其它符号function creatSelectTree(d){ var option=""; for(var i=0;i<d.length;i++){ if(d[i].children.length){//如果有子集  option+="<option value='"+d[i].id+"'>"+j+d[i].name+"</option>"; j+="-";//前缀符号加一个符号  option+=creatSelectTree(d[i].children);//递归调用子集 j=j.slice(0,j.length-1);//每次递归结束返回上级时，前缀符号需要减一个符号  }else{//没有子集直接显示  option+="<option value='"+d[i].id+"'>"+j+d[i].name+"</option>";  }  } return option;//返回最终html结果 }//调用函数，并将结构出入到下拉框容器中selectbox.innerHTML=creatSelectTree(tree);