How to insert space every 4 characters for IBAN registering?

Question

I\'m really new in JavaScript and I would like to add to my input text, space insertion for IBAN account registering.

Answer 1

I need the same but for BVR/BVR+ swiss payment form. So what I need is add a space every 5 chars but from the end of the string.

Example : "52 86571 22001 00000 10520 15992" or sometimes shorter like "843 14293 10520 15992".

So, here is the solution by reversing the string before and after adding spaces if rev=1.

function space(str, stp, rev) {
    if (!str) {
        return false;
    }
    if (rev == 1) {
        str = str.split('').reverse().join('');
    }
    if(stp > 0) {
        var v = str.replace(/[^\dA-Z]/g, ''),
            reg = new RegExp(".{" + stp + "}", "g");
        str = v.replace(reg, function (a) {
            return a + ' ';
        });
    }
    if (rev == 1) {
        str = str.split('').reverse().join('');
    }
    return str;
}

Use :

var refTxt = space(refNum, 5, 1);

EDIT : PHP version added

function space($str=false, $stp=0, $rev= false) {

    if(!$str)
        return false;
    
    if($rev)
        return trim(strrev(chunk_split(strrev($str), $stp, ' ')));
    else
        return trim(chunk_split($str, $stp, ' '));
}