取消空格js与动态加入多个上传文件

 /** 修剪字串前后的空格  */  function trim(s) {     var count = s.length;     var st    = 0;       // start     var end   = count-1; // end       if (s == "") return s;     while (st < count) {       if (s.charAt(st) == " ")         st ++;       else        break;     }     while (end > st) {       if (s.charAt(end) == " ")         end --;       else        break;     }     return s.substring(st,end + 1);   }   //动态加入多个上传文件框function addMore() {var td = document.getElementById("more");var br = document.createElement("br");var input = document.createElement("input");var button = document.createElement("input");input.type = "file";//类型input.name = "file";//name值button.type = "button";//类型button.value = "Remove";//value值//写事件//表示的意思是input的button按键事件button.onclick = function() {//删除td.removeChild(br);td.removeChild(input);td.removeChild(button);}td.appendChild(br);//在td中添加<br>标签td.appendChild(input);//在td中添加<input>标签td.appendChild(button);//在td中添加<input>标签}