使用javascript进行表单验证（带有格式的注册表单）

Question

我正在尝试验证每个字段并使用定义的格式显示适当的错误消息。用户名显示适当的错误消息，但其余代码不起作用。电子邮件字段正常工作，但是在将变量存储在atEmail和dotEmail之后，它不再起作用。我已经尝试了几天了。任何建议，我们将不胜感激。

function validateForm（）{

var firstPassword = document.myForm.passwordOne.value;
var secondPassword = document.myForm.passwordTwo.value; 
var emailID = document.myForm.email.value;
var alphaNumeric = /^[\w ]+$/;
var letters = /^[A-Za-z]+$/;
var atEmail = emailID.indexOf("@");
var dotEmail = emailID.lastIndexOf(".");
var phone = /^\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/;

 if(!alphaNumeric.test(document.myForm.userName.value)) {
    alert( "Please enter letters and numbers only!" );
    document.myForm.userName.focus() ;
    return false;
 }

 if(firstPassword.value.length < 8) {
    alert( "Password must be at least 8 characters" );
    document.myForm.passwordOne.focus() ;
    return false;
 }

 if(document.myForm.firstPassword.value != document.myForm.secondPassword.value ) {
    alert( "Password must match!" );
    document.myForm.passwordTwo.focus() ;
    return false;
 }

 if(!letters.match(document.myForm.firstName.value)) {
    alert( "Your first name should only contain letters!" );
    document.myForm.firstName.focus() ;
    return false;
 }

 if(!letters.match(document.myForm.lastName.value)) {
    alert( "Your last name should only contain letters!" );
    document.myForm.lastName.focus() ;
    return false;
 }

 if (atEmail < 1 || ( dotEmail - atEmail < 2 )) {
    alert("Please enter valid email address format: [email protected]");
    document.myForm.email.focus() ;
    return false;
 }

 if(phonenumber.value.match(phone)) {
    alert( "Please enter valid phone number format:(xxx) xxx-xxxx" );
    document.myForm.phonenumber.focus() ;
    return false;
 }

 if((document.myForm.signUpNewletter[0].checked == false) &&(document.myForm.signUpNewletter[1].checked == false )) {
    alert( "Please check yes or no!" );
    document.myForm.signUpNewsletter.focus() ;
    return false;
 }

 return true;

}

Answer 1

if(document.myForm.firstPassword.value != document.myForm.secondPassword.value ) {

您已经定义了firstPassword和secondPassword变量，然后为什么要在document.myForm.firstPassword和document.myForm.secondPassword中使用它们>