js验证上传的文件是否为JPEG，PNG，JPG，GIF格式

function checkPhoto(){
var type="";
if(document.getElementById("newphoto").value!=''){
type=document.getElementById("newphoto").value.match(/^(.*)(\.)(.{1,8})$/)[3];
type=type.toUpperCase();
}

if(type!="JPEG"   &&   type!="PNG"   &&   type!="JPG"   &&   type!="GIF"){
alert("上传图片类型错误");
return false;
}
}

form表单，验证文件类型，文本是否为空，文本长度验证js<script type="text/javascript">//进入下一步function subForm(){form1.submit();//form1为form的id}//表单验证$(function(){$("#addsubmit").click(function(){//表单校验if(validate()){$("#form1").submit();}});//进入文本框 隐藏错误提示框$("input").click(function(){$("#errorId").hide();});});//进行js校验 表单function validate(){var title =$.trim( $("#title").val());var content = $.trim($("#content").val());if(title == ""){//显示错误提示框$("#title").show();alert("标题不能为空")$("#title").html("标题不能为空");return false;}if(content == ""){//显示错误提示框$("#content").show();alert("内容不能为空")return false;}if(title.length>50){//显示错误提示框$("#title").show();alert("标题字数不能超过50字")$("#title").html("标题字数不能超过50字");return false;}var type="";if(document.getElementById("pic").value!=''){type=document.getElementById("pic").value.match(/^(.*)(\.)(.{1,8})$/)[3];type=type.toUpperCase();}if(type!="JPEG" && type!="PNG" && type!="JPG" && type!="GIF"){alert("上传图片类型错误,只能上传JPEG，png,jpg类型图片");return false;}return true;}</script>form<form id="form1" action="${pageContext.request.contextPath}/information/updateInformation.shtml" method="post" enctype="multipart/form-data"><input name="loginId" type="hidden" value="${userInfo.loginId}"/><input name="schschoolId" type="hidden" value="${userInfo.schschoolId}" /><input name="id" type="hidden" value="${information.id}" /><span class="left">文章标题：</span><input id="title" type="text" class="text left w350 mr20" name="title" value="${information.title }" /><span class="left">是否仅限本校学生查看：</span><div class="dropdown text w80 mr20"><select id="select_k1" class="shadow" name="display" ><option value="1" <c:if test="${information.display==1 }"> selected</c:if> >是</option><option value="0" <c:if test="${information.display==0 }"> selected</c:if> >否</option></select><!-- 登陆id --></div><span class="left">类型：</span><div class="dropdown text w80 mr20"><select name="type" id="select_k1" class="shadow"><option value="1" <c:if test="${information.type==1 }"> selected</c:if> >高校专版</option><option value="2" <c:if test="${information.type==2 }"> selected</c:if>>发现</option></select></div><span class="left">是否为轮播图：</span><div class="dropdown text w80 mr20"><select name="isFigure" id="select_k1" class="shadow"><option value="0" <c:if test="${information.isFigure==0 }"> selected</c:if>>否</option><option value="1"<c:if test="${information.isFigure==1 }"> selected</c:if>>是</option></select></div><c:if test="${!empty information.coverImgUrl }"><img src="${ information.coverImgUrl }" /></c:if><span class="left" style="width:80px; height:15px;"></span><span class="left" >封面图：</span><input id="pic" type="file" class="text left w200 mr10" name="pic" value="${ information.coverImgUrl }" /><textarea id="content" name="content" style="width:98%; height:185px;">${content }</textarea><div class="text-box pr30"><div class="btn-box"><!--part--><div class="part tr"><!-- <a title="发布" class="blue-btn btn-big mr10" onclick="subForm();">修改</a>--><a title="发布" id="addsubmit" href="javascript:;" class="blue-btn btn-big mr10">发布</a><a title="取消" class="btn gray-btn btn-big mr10" href="informationList.shtml">取消</a></div><!--part end--></div></div></form>