How to insert table row if and only if first cell value of a row is not equals to first cell value of next row?

             <table>
                <tr>
                   <td>aaa</td>
                   <td>111</td>
                </tr>
                <tr>
                   <td>aaa</td>
                   <td>222</td>
                </tr>
                <tr>
                   <td>bbb</td>
                   <td>111</td>
                </tr>
                <tr>
  开发者_开发知识库                 <td>bbb</td>
                   <td>222</td>
                </tr>
             </table>

In this example second row first cell value 'aaa' and third row first cell value 'bbb' are not same. Now How to add a new table row between second row and third row.

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You can use $() to create elements from markup, and insertBefore() to add them before a specific element:

$("tr").each(function() {
    var $prev = $(this).prev("tr");
    if ($prev.length
        && $("td:first", $prev).text() != $("td:first", this).text()) {
        $("<tr><td>New</td><td>Row</td></tr>").insertBefore(this);
    }
});