查找表标题单元格值（第一列）

Question

I have a HTML table as listed in http://jsfiddle.net/Lijo/sP7zD/ . I need to read the value of first column's header. I am doing it with “gt” and “lt” operators. But it is not getting the first column value.

1. What jQuery code change need to be done in the script that I wrote?
2. What is the better way for reading the value of first column's header?

CODE

<input type="submit" value="Alert" class="alertButton"/>


<table class="resultGridTable" cellspacing="0" id="detailContentPlaceholder_grdLocalTaxReport"
style="border-collapse: collapse;">
<tr>
    <th scope="col">
        IsSummaryRow
    </th>
    <th scope="col">
        Associate
    </th>
    <th scope="col">
        Gross Amount
    </th>
    <th scope="col">
        Federal Withholding
    </th>


</tr>
<tr>
    <td>
        False
    </td>
    <td>
        Norman Tylor
    </td>
    <td>
        3450
    </td>
    <td>
        32
    </td>
</tr>
</table>

<script type="text/javascript" src="http://ajax.aspnetcdn.com/ajax/jquery/jquery-1.4.1.js"></script>

​SCRIPT

$('.alertButton').click(function() {                                                  
    var selectedElements = $("tr").find("th:gt(0):lt(1)");
    $(selectedElements).css('background-color','yellow');
    alert(selectedElements.html());
});

​

Answer 1

Use $('th:first')

var selectedElements = $("th:first");

Here is the demo .

For your code: change to use eq instead.

var selectedElements = $("tr").find("th:eq(0)");

Answer 2

To answer question 1, your code tries to find the element with an index greater than 0, so it finds the second. Try removing the gt . This will find the element with an index less than 1, so it will match the element with an index of 0.

var selectedElements = $("tr").find("th:lt(1)");

But there are better ways of doing this, as mentioned in other answers.

Answer 3

Try this

HTML CODE

<input type="submit" value="Alert" class="alertButton" />
<table class="resultGridTable" cellspacing="0" id="detailContentPlaceholder_grdLocalTaxReport"
style="border-collapse: collapse;">
    <tr>
        <th scope="col">
            IsSummaryRow
        </th>
        <th scope="col">
            Associate
        </th>
        <th scope="col">
            Gross Amount
        </th>
        <th scope="col">
            Federal Withholding
        </th>
    </tr>
    <tr>
        <td>
            False
        </td>
        <td>
            Norman Tylor
        </td>
        <td>
            3450
        </td>
        <td>
            32
        </td>
    </tr>
</table>
<script type="text/javascript" src="http://ajax.aspnetcdn.com/ajax/jquery/jquery-1.4.1.js">
</script>

JS CODE

$('.alertButton').click(function()
    {                                                 
        var selectedElements = $('th').first();
            alert(selectedElements .text());
        selectedElements.css({'background':'yellow'});                 
});

DEMO

Answer 4

Use var selectedElements = $(".resultGridTable").find("tr:first").find('th:first');

$('.alertButton').click(function()
{

var selectedElements = $(".resultGridTable").find("tr:first").find('th:first');
    $(selectedElements).css('background-color','yellow');
    alert(selectedElements.html());


});

​