Validating a field that isn't required in javascript

[rush it]

How can I validate a phone number field that isn't required for a form? I'm well aware of the argument about including fields on a form that aren't required. It's not my call, it's the client's. Anyway, there is a Work Phone field on the form that I'd like to validate for the users who DO fill it in. Of course, I want it to be in US phone number format. Here's what I have for the phone fields that are required:

var regexObj = /^\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/;

	if (regexObj.test(document.forms["form1"]["phone"].value)) {
    
	} else {
    	alert("Please enter Phone Number as:  555-555-5555");
    	return false;
	}

This works flawlessly for the fields that require it. However, I can't find an edit so if the user doesn't enter it, validation just skips it.

My email validation script only validates if the user fills it in. It's not a required field either. Here's that code:

if (document.form1.email.value.length >0) {
	 i=document.form1.email.value.indexOf("@")
	 j=document.form1.email.value.indexOf(".",i)
	 k=document.form1.email.value.indexOf(",")
	 kk=document.form1.email.value.indexOf(" ")
	 jj=document.form1.email.value.lastIndexOf(".")+1
	 len=document.form1.email.value.length

 	if ((i>0) && (j>(1+1)) && (k==-1) && (kk==-1) && (j-i>1) &&(len-jj >=2) && (len-jj<=3)) {
 	}
 	else {
 		alert("Please enter your email address as: yourname@yourisp.com (or .net, .org, etc.)\n" );
		
		return false;
 	}
}

Again, this works flawlessly. With '>O' at the end of the first line, it only validates if the user filled it in; otherwise it gets skipped. Anyone else run into this?

[Dormilich]

maybe something along

if (form_field.value.length)
    // do validation

[rush it]

Since what I'm trying to conditionally validate is a phone number using a regular expression, that line doesn't work. It allows the form to submit before it's finished. I'm thinking the regular expression is the problem. Maybe there's not a way around it. I'm new to web design and programming and I've only used regular expressions to validate phone numbers, so I'm going to do look for other validation methods.

[Rabbit]

I don't understand. Aren't you trying to achieve for the phone number the same thing you did for the e-mail? Just use the same concept.

[rush it]

It's easy to talk about 'concepts' when you're a seasoned programmer but when you're not, like me, actual syntax helps - at least the first time around. A co-worker helped me see how to use Dormilich's suggestion in my syntax. I just needed to go one step further. Thanks Dormilich.