JavaScript-表格-验证数字和电子邮件

Question

I am not great with scripting or coding, so I'm really sorry if this is a silly question.

I have a form:

<form name="userinfo" action="validform.html" method="post" onsubmit="return validateForm()">
    <fieldset>
        <legend>Personal Information</legend><br />

        <label for="firstname">First Name:</label>
        <input type="text" id="firstname" name="firstname">
        <span id="firstname_required"></span><br />

        <label for="surname">Surname:</label>
        <input type="text" id="surname" name="surname">
        <span id="surname_required"></span><br />

        <label for="tel">Tel No:</label>
        <input type="tel" id="tel" name="tel">
        <span id="tel_required"></span><br />

        <label for="email">Email:</label>
        <input type="email" id="email" name="tel">
        <span id="email_required"></span><br />

        <label for="password">Password:</label>
        <input type="password" id="password" name="password">
        <span id="password_required"></span><br />

        <label for="submit"></label>
        <input type="submit" value="Submit!">
    </fieldset>
</form>

The form works great.

I would like to validate the Tel No, so that only digits between 0-9 can be entered. I'm not worried about length or anything rock n roll like that. I just want to make sure that users enter in numbers, then I can expand on that. Here is my code:

function validateNumber()
{
        var a=document.forms["userinfo"]["tel"].value;
        var patt=new RegExp("[0-9]");

        if (a==null || a=="")
        {
         document.getElementById('tel_required').innerHTML="required";
        }
        else if (patt==null || patt !== RegExp )
        {
             document.getElementById('tel_required').innerHTML="numbers only allowed";
        }
}

I suspect I have something fundamentally wrong in my else if statement ((patt==null || patt !== RegExp )) or that it's even constructed correctly, or that it should even be an else if statement!! But I can't even seem to get the logic quite right in my head.

Any help would be great. Thanks, and again sorry if this is a silly question.

Here is the full JavaScript code I have so far:

function validateForm()
    {
        var a=document.forms["userinfo"]["firstname"].value;

        if (a==null || a=="")
                {
                    document.getElementById('firstname_required').innerHTML="required";
                }


        var a=document.forms["userinfo"]["surname"].value;

        if (a==null || a=="")
            {
                document.getElementById('surname_required').innerHTML="required";
            }

validateNumber()
validateEmail()


        var a=document.forms["userinfo"]["password"].value;

        if (a==null || a=="")
            {
                document.getElementById('password_required').innerHTML="required";
                return false;
            }

    }

function validateNumber()
{
var a=document.forms["userinfo"]["tel"].value;
var patt=new RegExp("[0-9]");

if (a==null || a=="")
            {
                document.getElementById('tel_required').innerHTML="required";
            }

 if (patt==null || patt !== RegExp )
            {
                document.getElementById('tel_required').innerHTML="numbers only allowed";
            }
}


function validateEmail()
{
var a=document.forms["userinfo"]["email"].value;
var patt=new RegExp("/^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$/");

if (a==null || a=="")
            {
                document.getElementById('email_required').innerHTML="required";
            }
} 

Answer 1

If you are lucky enough to be HTML5, you might be able to get away with

<input type="number">

Try input type=number to see the HTML5 version in action.

else try below code

function validateNumber()
{
        var a=document.forms["userinfo"]["tel"].value;

        if (a==null || a=="")
        {
         document.getElementById('tel_required').innerHTML="required";
        }
        else if (/[^\d]/.test(a)) 
        {

             document.getElementById('tel_required').innerHTML="numbers only allowed";
        }
    else {
         document.getElementById('tel_required').innerHTML="input OK";
         }
    }

Answer 2

As Novocaine88 says, you should also allow spaces.

if (!/[^\d ]/.test(a)) {
    //OK
} else {
    //not OK - contains character(s) other than numbers/spaces
}

Note the simpler method of declaring a regular expression, also, via the literal /pattern/ rather than the constructor.