jquery字符串操作

///<reference path="jquery-1.3.1-vsdoc.js" />
$("document").ready(
function() {
    $(":checkbox").click(
    function() {
        var textbox_text =$("#ctl00_ContentPlaceHolder1_TextBox_label").val();//存放关键字的textbox
       
        if ($(this).attr("checked")) {
            if (textbox_text.indexOf($(this).parent().children("label").text())>=0)
            { }
            else {
                var textbox_text_now = textbox_text + $(this).parent().children("label").text() + " ";
                $("#ctl00_ContentPlaceHolder1_TextBox_label").val(textbox_text_now);
            }
        }
        else {
            var textbox_text_now = textbox_text.replace($(this).parent().children("label").text(),"");
            $("#ctl00_ContentPlaceHolder1_TextBox_label").val(textbox_text_now);

        }
    })
})