js判断上传文件格式

[javascript]代码库

	function isPicFile(fileName) {
			//lastIndexOf如果没有搜索到则返回为-1
			if (fileName.lastIndexOf(".") != -1) {
				var fileType = (fileName.substring(
						fileName.lastIndexOf(".") + 1, fileName.length))
						.toLowerCase();
				var suppotFile = new Array();
				suppotFile[0] = "jpg";
				suppotFile[1] = "gif";
				suppotFile[2] = "bmp";
				suppotFile[3] = "png";
				suppotFile[4] = "jpeg";
				suppotFile[5] = "png";
				for ( var i = 0; i < suppotFile.length; i++) {
					if (suppotFile[i] == fileType) {
						return true;
					} else {
						continue;
					}
				}
				showMsg("文件类型不合法,只能是jpg、gif、bmp、png、jpeg、png类型！");
				return false;
			} else {
				showMsg("文件类型不合法,只能是 jpg、gif、bmp、png、jpeg、png类型！");
				return false;
			}
	}