Javascript/jQuery breaks the formatting of the page

Question

The formatting of my page is incorrect when I add the following code:

$('#Inventory_accountNumber').blur(function(){
    var accounts = $(this).val();
    accounts = accounts.replace(/-/g,'');
    var accountNum = [];
    accountNum = accounts.split(",");
    for(var i=0;i<accountNum.length;i++) {
        var newstr = '';
        if(accountNum[i].length == 24) {
            newstr += accountNum[i].substring(0,4) + '-';
            newstr += accountNum[i].substring(4,7) + '-';
            newstr += accountNum[i].substring(7,10) + '-';
            newstr += accountNum[i].substring(10,14) + '-';
            newstr += accountNum[i].substring(14,20) + '-';
            newstr += accountNum[i].substring(20,24) + '-';
            newstr += '0000-000';
            accountNum[i] = newstr;
        }
        else if(accountNum[i].length == 31) {
            newstr += accountNum[i].substring(0,4) + '-';
            newstr += accountNum[i].substring(4,7) + '-';
            newstr += accountNum[i].substring(7,10) + '-';
            newstr += accountNum[i].substring(10,14) + '-';
            newstr += accountNum[i].substring(14,20) + '-';
            newstr += accountNum[i].substring(20,24) + '-';
            newstr += accountNum[i].substring(24,28) + '-';
            newstr += accountNum[i].substring(28,31);
            accountNum[i] = newstr;
        }
    }
    accountNum.join(',');
    $(this).val(accountNum);

});

The jsfiddle illustrates this code in use: http://jsfiddle.net/Lwv4U/14/

As you can see, it works in the jsfiddle, but on the live formatting issues are present. The screenshots below depict the page with and without the code added. This code is the only change in the code between the two code bases. If it matters Yii is being used as a framework.

Before

After

Answer 1

jsfiddle.net/Lwv4U/25

JS:

$('#Inventory_accountNumber').blur(function(){
  $(this).val(function(index, value){
    var str = value.replace(/[^\d]/g,'');
    if (str.length < 10) return str;  
    return str.match(/(\d{4})?(\d{3})?(\d{3})?(\d{4})?(\d{6})?(\d{4})?(\d{4})?(\d+)?/)
    .slice(1).join("-").replace(/\-+/g,'-');
  });
});