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Complex Regular Expression for a form validation

Posted on 2013-01-05

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Last Modified: 2013-01-05

I have this form that validates with jquery & regular expressions...

...
//some code

var characterReg = /^([a-zA-Z0-9]{2,50})$/; //only letters and numbers

if ( !characterReg.test(inputValName) ){

			result.text('that\'s not a valid name!');

...
//more code

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Now, I need a very specific validation of a field called 'NIF', wich is the identifier of a tax-paying company in my country. And I need some help to make a regular expression to use like I did in the above code.

So I found an old javascript code online that validates 'NIF':

function IsValidNIF(nif)
{
    var c;
    var checkDigit = 0;
    //Check if is not null, is numeric and if has 9 numbers
    if(nif != null && IsNumeric(nif) && nif.length == 9)
    {
        //Get the first number of NIF
        c = nif.charAt(0);
        //Check firt number is (1, 2, 5, 6, 8 or 9)
        if(c == ‘1' || c == ‘2' || c == ‘5' || c == ‘6' || c == ‘8' || c == ‘9')
        {
            //Perform CheckDigit calculations
            checkDigit = c * 9;
            var i = 0;
            for(i = 2; i <= 8; i++)
            {
                checkDigit += nif.charAt(i-1) * (10-i);
            }
            checkDigit = 11 - (checkDigit % 11);
            //if checkDigit is higher than ten set it to zero
            if(checkDigit >= 10)
                checkDigit = 0;
            //Compare checkDigit with the last number of NIF
            //If equal the NIF is Valid.            
            if(checkDigit == nif.charAt(8))
                return true;            
        }        
    }
    return false;
}

function IsNumeric(ObjVal)
{
return /^\d+$/.test(ObjVal);
}

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So, is it possible to make a regular expression from this?

The rules are:

-must be only numbers
-must be 9 characters(numbers) long
-the first number must be 1 or 2 or 5 or 6 or 8 or 9
-the last number performs some validation(%module) that you should understand viewing the above code

Thank you.

Comment

Question by:joao_c

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11 Comments

LVL 84

Expert Comment

by:ozo

ID: 387469392013-01-05

-must be only numbers
-must be 9 characters(numbers) long
-the first number must be 1 or 2 or 5 or 6 or 8 or 9
characterReg = /^[125689][0-9]{8}$/

-the last number performs some validation(%module) that you should understand viewing the above code
This part would produce a more complicated regular expression than is worth it, so I'd stick to using code.

Author Comment

by:joao_c

ID: 387469812013-01-05

What you mean " ...I'd stick to using code." ?

If possible let me know "how" complicated would the regex become. I don't mind if the regex is not "readable", the aproach of regex is just to cut some lines of code. Unless the regex could have some performance/other issues,. is that the case?

Thanks a lot.

LVL 75

Expert Comment

by:käµfm³d 👽

ID: 387470272013-01-05

I have to agree with ozo: You're going to be attempting to reproduce modulo arithmetic via a regex. This isn't really what regex is designed for. The code approach would be much simpler. Just use ozo's suggested pattern, then add logic for the modulo check.

Author Comment

by:joao_c

ID: 387471162013-01-05

Thanks kaufed.

Then how would I add up the 2 things (regex + code) in my form?

Should be like:

...
//some code

var myRegex = /^[125689][0-9]{8}$/;

if ( myRegex.test(inputValName) ){

			// then implement other if here with the modulo% code??

...
//more code

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LVL 82

Expert Comment

by:leakim971

ID: 387471242013-01-05

What about :

String.prototype.ozo = function(i) { return this.charAt(i-1) * (10-i); }
function IsValidNIF(nif) {
	var checkDigit = 0;
	for(var i=1;i<9;i++) checkDigit += nif.ozo(i);
	return /^[125689][0-9]{8}$/.test(nif) && ((checkDigit%11 >= 21)?0:checkDigit == nif.charAt(8));
}

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Author Comment

by:joao_c

ID: 387471562013-01-05

Thanks for the reply leakim971.

That's a little scary for my modest understanding of jquery.

Where do I put that code in the current code I have??

	<script>


	function clearInput() {
		$("#myForm :input").each( function() {
			$(this).val('');
		});
	};



	$("#submitBtn").click( function() {


		var result = $('#result');
		var company = $('#myForm > #name-of-company');
		var ai = $('#myForm > #annual-income');
		var characterReg = /^([a-zA-Z0-9]{2,50})$/; //only letters and numbers
		var aiReg = /^([0-9]{3,15})$/; //only numbers
		var inputVal = ai.val();
		var inputValName = company.val();

		if ( !characterReg.test(inputValName) ){

			result.text('that\'s not a valid name!');
			company.addClass('wrong');
			

		} else if ( !aiReg.test(inputVal) ) {

			result.text('only numbers!');
			ai.addClass('wrong');
			company.removeClass('wrong');



		} else {

			$.post( $("#myForm").attr("action"), 
			$("#myForm :input").serializeArray(), 
			function(info){ result.html(info);
			});
			clearInput();
			company.removeClass('wrong');
			ai.removeClass('wrong');

		};


	});



	$("#myForm").submit( function() {
		return false;	
	});



	</script>

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LVL 82

Expert Comment

by:leakim971

ID: 387471662013-01-05

There's no query here. You need to replace your current function by the one provided

Author Comment

by:joao_c

ID: 387473142013-01-05

but i a working with jquery here, I am more familiar with with. Don't know how to manipulate the DOM with pure js. Can I incorporate that function in my jquery?

Thanks

LVL 82

Expert Comment

by:leakim971

ID: 387473182013-01-05

just replace your previous one, no more no less...

LVL 75

Accepted Solution

by:käµfm³d 👽

käµfm³d 👽 earned 500 total points

ID: 387473722013-01-05

Modifying your existing code:

function IsValidNIF(nif)
{
    var checkDigit = 0;
    var i = 0;
    var characterReg = /^[125689][0-9]{8}$/;
    
    if (characterReg.test(nif) {
        //Perform CheckDigit calculations
        checkDigit = nif.charAt(0) * 9;

        for(i = 2; i <= 8; i++)
        {
            checkDigit += nif.charAt(i-1) * (10-i);
        }

        checkDigit = 11 - (checkDigit % 11);

        //if checkDigit is higher than ten set it to zero
        if(checkDigit >= 10)
            checkDigit = 0;

        //Compare checkDigit with the last number of NIF
        //If equal the NIF is Valid.            
        if(checkDigit == nif.charAt(8))
            return true;
    }

    return false;
}

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Note: The IsNumeric shouldn't be needed anymore--at least not for this function.

Author Closing Comment

by:joao_c

ID: 387481182013-01-05

Thank you, it works great.

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