js判斷文件類(lèi)型大小并給出提示的實(shí)現(xiàn)方法

<form id="uploadForm" method="post" class="layui-form">
  <div class="layui-form-item">
  <label class="layui-form-label">名稱(chēng)</label>
  <div class="layui-input-block">
   <input type="text" name="name" required lay-verify="required"
   placeholder="請(qǐng)輸入文件名" autocomplete="off" class="layui-input">
  </div>
  </div>
  <div class="layui-form-item">
  <label class="layui-form-label">資料類(lèi)型:</label>
  <div class="layui-input-block">
   <select name="datatypeid" id="datatypeid"></select>
  </div>
  <input type="hidden" id="yincang">
  </div>
  <div class="layui-form-item">
  <label class="layui-form-label">上傳文件</label>
  <div class="layui-input-block">
   <input class="layui-input" type="file" name="file" onchange="fileChange(this);"/>
  </div>
  </div>
  <div class="layui-form-item">
  <div class="layui-input-block">
   <input type="button" class="layui-btn" value="上傳"
   onclick="upload()" />
  </div>
  </div>
 </form>

<script type="text/javascript">
 var isIE = /msie/i.test(navigator.userAgent) && !window.opera;
 function fileChange(target, id) {
  var fileSize = 0;
  var filetypes = [ ".doc", ".docx" ];//這里設(shè)置接受的文件類(lèi)型
  var filepath = target.value;
  var filemaxsize = 1024 * 10;//接受的文件最大10M 
  if (filepath) {
  var isnext = false;
  var fileend = filepath.substring(filepath.indexOf("."));
  if (filetypes && filetypes.length > 0) {
   for (var i = 0; i < filetypes.length; i++) {
   if (filetypes[i] == fileend) {
    isnext = true;
    break;
   }
   }
  }
  if (!isnext) {
   alert("不接受此文件類(lèi)型！");
   target.value = "";
   return false;
  }
  } else {
  return false;
  }
  if (isIE && !target.files) {
  var filePath = target.value;
  var fileSystem = new ActiveXObject("Scripting.FileSystemObject");
  if (!fileSystem.FileExists(filePath)) {
   alert("附件不存在，請(qǐng)重新輸入！");
   return false;
  }
  var file = fileSystem.GetFile(filePath);
  fileSize = file.Size;
  } else {
  fileSize = target.files[0].size;
  }
  var size = fileSize / 1024;
  if (size > filemaxsize) {
  alert("附件大小不能大于" + filemaxsize / 1024 + "M！");
  target.value = "";
  return false;
  }
  if (size <= 0) {
  alert("附件大小不能為0M！");
  target.value = "";
  return false;
  }
 }
 </script>