document.writeln(" <SCRIPT LANGUAGE=\"JavaScript\">");
document.writeln("function checkmail()");
document.writeln("{");
document.writeln(" if(document.youjian.useremail.value.length!=0)");
document.writeln("  {");
document.writeln("    if (document.youjian.useremail.value.charAt(0)==\".\" ||        ");
document.writeln("         document.youjian.useremail.value.charAt(0)==\"@\"||       ");
document.writeln("         document.youjian.useremail.value.indexOf(\'@\', 0) == -1 || ");
document.writeln("         document.youjian.useremail.value.indexOf(\'.\', 0) == -1 || ");
document.writeln("         document.youjian.useremail.value.lastIndexOf(\"@\")==document.youjian.useremail.value.length-1 || ");
document.writeln("         document.youjian.useremail.value.lastIndexOf(\".\")==document.youjian.useremail.value.length-1)");
document.writeln("     {");
document.writeln("      alert(\"Email地址格式不正确！\");");
document.writeln("      document.youjian.useremail.focus();");
document.writeln("      return false;");
document.writeln("      }");
document.writeln("   }");
document.writeln(" else");
document.writeln("  {");
document.writeln("   alert(\"Email不能为空！\");");
document.writeln("   document.youjian.useremail.focus();");
document.writeln("   return false;");
document.writeln("   }");
document.writeln("}");
document.writeln("<\/script> ");