[学习笔记]验证上传文件后缀名类型

<script type="text/javascript" charset="utf-8">
			function checkFile(filename){
					var flag = false;
					var arr = ["jpg","png","gif","bmp"];
					//取扩展名；
					var index = filename.indexOf(".");
					var ext = filename.substr(index+1);

					for(var i = 0; i<arr.length; i++){
						if(ext==arr[i]){
						flag = true;
						break;
						 								}
						}
					if(flag){
					document.write("合法");
					}else{
					document.write("不合法");
					}

			}

		</script>

<form name="form" method="post" enctype="multipart/form-data">
		上传图片：<input id="button" type="file" name="uploadType"  onchange="checkFile(this.value)"/>
		</form>