Using JQuery to determine if a table contains a row with specific content

Question

I have this html table (vastly simplified to protect the innocent)...

<table id="codeList">
<thead> 
    <tr>
        <th>Code</th>
    </tr>
</thead>
<tbody>
    <tr>
        <td>Code1 <input type="hidden" name="code1" value="123"/></td>
    </tr>
        <tr>
        <td>Code2 <input type="hidden" name="code2" value="456"/></td>
    </tr>
    <tr>
        <td>Code3 <input type="hidden" name="code3" value="789"/></td>
    </tr>
</tbody>

...and I'm trying to determine in a javascript method if the code is already in the table...

if (!$('#codeList >tbody').is( ":contains('456')")) {
    $("#codeList > tbody:last").append("<tr>" +
    "<td> Code2 <input type='hidden' name='code2' value='456'/></td>" +
    "</tr>");
}

...which isn't working. Basically, I need a JQuery expression that can search the rows of the table, checking the value of each hidden field to see if it already exists and return true/false, or at least behave like true/false for the purposes of a javascript conditional. This is a bit different from most scenarios that I see in that I need to determine if a row doesn't exist and then act on the table. Most people want to select rows that DO exist and then act on them.

Answer 1

Don't use :contains for attribute values, use the attribute equals selector :

if (!$('#codeList input[value="456"]').length) {
   // do something
}

That is select any inputs with that value that are descendents of #codeList and if none are found then .length will be 0...

Answer 2

if (!$("#codeList input[value='456']")[0]) {
    $("#codeList > tbody:last").append("<tr>" +
    "<td> Code2 <input type='hidden' name='code2' value='456'/></td>" +
    "</tr>");
}

Answer 3

if (!$('#codeList input[value="456"]').length) {
 $("#codeList > tbody:last").append("<tr>" +
  "<td> Code2 <input type='hidden' name='code2' value='456'/></td>" +
  "</tr>");
}