jsonp实现百度下拉框功能的方法分析

var obj=document.querySelector('#user-input');
var body=document.querySelectorAll('body')[0];
var ul=document.querySelector('#ul');
var inner='';
function render(data){
    //删除前一次请求的li的内容
    if(ul.innerHTML!=''){
      ul.innerHTML='';
    }
    for(let i = 0, length1 = data.s.length; i < length1; i++){
      var li=document.createElement('li');
      li.innerHTML=data.s[i];
      ul.appendChild(li);
    }
}
obj.addEventListener('keyup',function(){
    if(document.querySelector('#request')){
      body.removeChild(document.querySelector('#request'));
    }
      var script=document.createElement('script');
      script.id="request";
      script.src="http://unionsug.baidu.com/su?wd="+encodeURI(obj.value.trim())+'&p=3&cb=render';
      body.appendChild(script);
});
//利用冒泡添加事件。
ul.addEventListener('click',function(e){
    var e=e||window.event;
    window.location.href="https://www.baidu.com/s?word=" rel="external nofollow" +encodeURI(e.target.innerHTML);
});

<style type="text/css">
  *{
          margin: 0;
          padding: 0;
  }
  ul{
          margin-left: 10px;
          transition: all 1s ease;
  }
    input{
          width: 300px;
          height: 40px;
          line-height: 40px;
          background: #4caf50a6;
          outline: none;
          border: none;
          border-radius: 10px;
          padding-left: 15px;
          color: white;
          font-size: 20px;
    }
    li{
          cursor: pointer;
          transition: all 1s ease;
          list-style: none;
          width: 280px;
          height: 30px;
          line-height: 30px;
          background: #8acb8da8;
          color: #888e4a;
          padding-left: 10px;
    }
    li:hover{
          background: #64a968;
          color: #caf1cc;
    }
    input::-webkit-input-placeholder{
      color:white;
    }
    input::-moz-placeholder{  /* Mozilla Firefox 19+ */
      color:white;
    }
    input:-moz-placeholder{  /* Mozilla Firefox 4 to 18 */
      color:white;
    }
    input:-ms-input-placeholder{ /* Internet Explorer 10-11 */ 
      color:white;
    }
</style>