.mybtn{
  width:100px;
  height:30px;
  display:inline-block;
  background-color:rgb(91,183,91);
  border:1px solid rgb(91,183,91);
  border-radius:3px;
  color:white;
  font-size:14px;
  font-family:微软雅黑;
  cursor:pointer;
  text-align:center;
  vertical-align: center;
  box-shadow:0px 0px 1px 1px rgb(91,160,91);
}
.mybtn:hover{
  background-color:rgb(91,160,91);
  border-color:rgb(91,160,91);
  color:white;
  text-decoration:none;
}
.myinp{
  width:100px;
  height:30px;
  display:inline-block;
  border:1px solid rgb(209,232,250);
  border-radius:2px;
}
#div4bm{
  padding-top:15px;
  margin-right:15px;
  }
  #mybutton{
  margin-left:100px;
}
#myimg{
  width:164px;
  height:164px;
}

//定义id选择器
function Id(id){
return document.getElementById(id);
}
function changeToop(){
  var file = Id("file");
  if(file.value==''){
    //设置默认图片
  Id("myimg").src='http://sandbox.runjs.cn/uploads/rs/72/huvtowwn/zanwu.png';
  }else{
    preImg("file","myimg");
  }
}
//获取input[file]图片的url Important
function getFileUrl(fileId) {
  var url;
  var file = Id(fileId);
  var agent = navigator.userAgent;
  if (agent.indexOf("MSIE")>=1) {
  url = file.value;
  } else if(agent.indexOf("Firefox")>0) {
  url = window.URL.createObjectURL(file.files.item(0));
  } else if(agent.indexOf("Chrome")>0) {
  url = window.URL.createObjectURL(file.files.item(0));
  }
  return url;
}
//读取图片后预览
function preImg(fileId,imgId) {
var imgPre =Id(imgId);
imgPre.src = getFileUrl(fileId);
}