JavaScript实现单图片上传并预览功能

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>单图片上传并实现预览</title>
 <style>
  /*上传图片*/
 .addPerson{
  line-height: 190px;
 }
 .addPhoto{
  width: 50px;
  height: 50px;
  line-height: 50px;
  font-size: 40px;
  text-align: center;
  vertical-align: middle;
  border: 1px dashed #e7eaec;
  cursor: pointer;
  display: inline-block;
 }
 .addinput{
  display: none;
 }
 .addShow{
  width: 200px;
  height: 170px;
  display: inline-block;
  vertical-align: middle;
  background: #f3f3f48f;
  margin-left: 30px;
 }
 .addShow img{
  width: 130px;
  height: 130px;
  margin: 20px auto;
  display: block;
 }
 </style>
</head>
<body>
 <div class=" addPerson">
 <label class="col-sm-2 control-label">图片上传</label>
  <div class="col-sm-9" style="display: inline-block;">
  <div class="addPhoto">+</div>
  <div class="addinput">
   <input type="file" class="addFile" onchange="previewFile()" name="sPicture">
  </div>
  <div class="addShow" style="position: relative">
   <img src="" class="addImg" alt="">
  </div>
  </div>
 </div>
</body>
<script src="https://cdn.staticfile.org/jquery/1.10.2/jquery.min.js"></script>
<script>

 $(".addPhoto").click(function () {
 $('[type=file]').click();
 });

 function previewFile() {
 var preview = document.getElementsByClassName("addImg")[0];
 var file = document.getElementsByClassName('addFile')[0].files[0];
 var reader = new FileReader();

 reader.addEventListener("load", function () {
 preview.src = reader.result;

 }, false);

 if (file) {
 reader.readAsDataURL(file);
 }

 // ajax请求如下

 // 使用FormData将图片以文件的形式传到后台
 // pictureFile后台接收的参数

 // var formdata=new FormData();
 // formdata.append("pictureFile",addFile);
 // $.ajax({
 //  url:"",
 //  type:"post",
 //  dataType:"json",
 //  data:formdata,
 //  async: false, //四个false属性不能少
 //  cache: false,
 //  contentType: false,
 //  processData: false,
 //  success:function (data) {
 //   if(data.success){
 //   myAlert(data.msg);
 //   }

 //  },
 //  error:function () {
 //   if(data.success){
 //   myAlert(data.msg);
 //   }

 //  }

 //  })
}
</script>
</html>