Conditional change of text colour inside table cell

问题

I'm try to use jQuery to conditionally change the color of some table cells. I have a table:

<tr>
<td>Class Code</td>
<td class="qty">3</td>
<td>Science</td>
</tr>
<td>Class Code</td>
<td class="qty">4</td>
<td>Science</td>
</tr>
. . . 

A style definition lowqty{color:red;}

I want to change the color of the second column when the number is below 4. I'm attempting to do that with the following, but haven't got it to work.

$('.qty').change(
function() {
    if ($(this).text() <= 3 ) {
        $(this).addClass('lowqty');
    }
    });

I've tried 3 as a string as well as a number, and I've tried filter and add in addition to change.

回答1:

$('.qty').each(function() {
    if (parseInt($(this).text()) < 4) {
        $(this).addClass('lowqty');
    }
});

That should do the trick. Also you're missing an opening TR tag:

http://jsfiddle.net/suDqH/

回答2:

Use .val() instead of .text() and that should work.

Also, you can't call a change event on a table cell - .change() is for select elements.

来源：https://stackoverflow.com/questions/15752923/conditional-change-of-text-colour-inside-table-cell