Question

I’m trying replace the index of form elements. I have the following

    var test = "<input name='[1].Id' value='598' type='hidden' /><input name='[1].OrderItemId' value='867' type='hidden' />";
    alert(test.replace('[1]', '[2]'));

I’m getting curious results. The first hidden field is replaced by the second is ignored

ie my response is something like this:

"<input name='[1].Id' value='598' type='hidden' /><input name='[2].OrderItemId' value='867' type='hidden' />"

EDIT:

OK, thanks these methods worked on my simple example. However in reality my string is a bit more complex. Here is the contents of “var lastRow “

<td>

                 <a class="deleteAddress" href="#">
                 <img alt="remove" src="/images/icons/delete_button.gif">
                 </a></td>
                <td class="p-5" width="100">
                   <input name="[1].Id" value="612" type="hidden">
                   <input name="[1].OrderItemId" value="868" type="hidden">
                   <input class="itemAddressQuantity" name="[1].Quantity" value="" type="text">

                </td>
               <td class="p-5" width="100">
               <select name="[1].AddressId"><option value="2">address1</option></select>                            
                </td>

and here is the js function

    $('#addNewAddress').click(function (event) {

        event.preventDefault();
        var length = $('.table-item-address tbody').find('tr').length;
       var previousLength = length - 1;
        var previousIndex = "/\[" + previousLength + "\]/g";
        var currentIndex = "[" + length + "]";
        var lastRow = $('.table-item-address tbody tr').last();
alert(lastRow.html()); // html is shown above
        var newRow = lastRow.html().replace(previousIndex, currentIndex);
        $('.table-item-address tr').last().after('<tr>' + newRow + '</tr>');
        AdjustValues();
    });

Answer 1

In JavaScript, passing a string as the first parameter to replace() will only replace the first occurrence. You need to use a regex, with the global flag:

test.replace(/\[1\]/g, '[2]');

The extra backslashes (\) escape the brackets ([ and ]).

---

Edit: responding to the OP’s edit, if you want to dynamically build a regex, you can’t use a regex literal – that’s the thing delimited by forward slashes (/), not quotes (") as in your edit. You’re passing a string into replace(), I’m passing in a regex literal. Use the JavaScript RegExp() constructor to fix yours:

// The first argument is the regex, the second is a string of flags.
var previousIndex = new RegExp("\\[" + previousLength + "\\]", "g");

// Then, it's exactly the same as before.
// The second argument to replace is still a string.
var newRow = lastRow.html().replace(previousIndex, currentIndex);

Note the difference in character escaping.