Clone a <tr> and also increment the name attribute of elements inside <td> by 1

Question

I've to implement a 'Add New Row' feature in a form. The structure of the form is something like:

<table>
<tr>
     <td><input type="text" name="v1[label]" /></td>
     <td><input type="text" name="v1[observation]" /></td>
     <td><input type="text" name="v1[remarks]" /></td>
</tr>
<tr>
     <td><input type="text" name="v2[label]" /></td>
     <td><input type="text" name="v2[observation]" /></td>
     <td><input type="text" name="v2[remarks]" /></td>
</tr>
<tr>
    <td colspan="3">
       <input type="button" id="addrow" value="Add One More Row">&nbsp;
       <input type="submit" name="proceed" value="Submit" />
    </td> 
</tr>
</table>

As seen, with each row, there is an increase in v[] number. v1, v2..and so on

WHAT I'M LOOKING FOR

When 'Add One More Row' button is clicked, the following things should happen

• A new row gets inserted just above the last row (the row with buttons)
• The name attribute value increases by 1 (i.e. v2[label] becomes v3[label], v2[observation] becomes v3[observation] and so on) in that row

WHAT I TRIED

The closest I came to was using jQuery's clone(). This does add the row perfectly. But I'm finding it difficult to find a way to increase the value of the name attribute by 1 each time the button is clicked.

jQUERY BEING USED CURRENTLY

$('input:button[id="addrow"]').click(function(){

   var secondlast = $('table tr:last').prev('tr');
   secondlast.clone().insertBefore(secondlast);

});

If I click the button two times, I'm getting the following HTML added

<tr>
     <td><input type="text" name="v2[label]" /></td>
     <td><input type="text" name="v2[observation]" /></td>
     <td><input type="text" name="v2[remarks]" /></td>
</tr>

<tr>
     <td><input type="text" name="v2[label]" /></td>
     <td><input type="text" name="v2[observation]" /></td>
     <td><input type="text" name="v2[remarks]" /></td>
</tr>

So a row is being added, but the name attribute remains at v2, whereas it should be v3 and v4 for the third and fourth row. I understand clone() can't do that and that is why I'm looking for an alternative.

Answer 1

$('input:button[id="addrow"]').click(function(){
    var secondlast = $('table tr:last').prev('tr');
    var newClone = secondlast.clone();
    // find all the inputs within your new clone and for each one of those
    newClone.find('input').each(function() {
        var currentNameAttr = $(this).attr('name'); // get the current name attribute
        // construct a new name attribute using regular expressions
        // the match is divided into three groups (indicated by parentheses)
        // p1 will be 'v', p2 will be the number, p3 will be the remainder of the string
        var newNameAttr = currentNameAttr.replace(/^(v)(\d+)(.*)$/, function(match, p1, p2, p3) {
            return p1+(parseInt(p2)+1)+p3;
        });
        $(this).attr('name', newNameAttr);   // set the incremented name attribute 
    });
    // insert after is I assume what you want
    newClone.insertAfter(secondlast);
});

Edit

// you could also simply increment any digit you find as Batman indicated
var newNameAttr = currentNameAttr.replace(/\d+/, function(match) {
    return (parseInt(match)+1);
});