<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>