javascript Form onSubmit 驗證函式

function send(){

var errorString = validate();

if(errorString.length > 0){

errorString = "您產生下列錯誤:\n" + errorString ;

alert(errorString);

}else{

document.form1.submit();

}

}

function validate(){
var errorString = "";
if(document.form1.order_name.value==""){
errorString = errorString + "請輸入訂購人姓名\n";
}
return errorString;
}
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<form name="form1" method="post" action="confirmation.php" onSubmit="send();return false">