$('input:radio[name="postage"]').change(
function(){
if ($(this).is(':checked') && $(this).val() == 'Yes') {
// append goes here
}
});
或者，上面 - 再次 - 使用一点less多余的 jQuery：
$('input:radio[name="postage"]').change(
function(){
if (this.checked && this.value == 'Yes') {
// note that, as per comments, the 'changed'
// <input> will *always* be checked, as the change
// event only fires on checking an <input>, not
// on un-checking it.
// append goes here
}
});
修改（改进了一些）jQuery：
// defines a div element with the text "You're appendin'!"
// assigns that div to the variable 'appended'
var appended = $('<div />').text("You're appendin'!");
// assigns the 'id' of "appended" to the 'appended' element
appended.id = 'appended';
// 1. selects '<input type="radio" />' elements with the 'name' attribute of 'postage'
// 2. assigns the onChange/onchange event handler
$('input:radio[name="postage"]').change(
function(){
// checks that the clicked radio button is the one of value 'Yes'
// the value of the element is the one that's checked (as noted by @shef in comments)
if ($(this).val() == 'Yes') {
// appends the 'appended' element to the 'body' tag
$(appended).appendTo('body');
}
else {
// if it's the 'No' button removes the 'appended' element.
$(appended).remove();
}
});
var appended = $('<div />').text("You're appendin'!");
appended.id = 'appended';
$('input:radio[name="postage"]').change(function() {
if ($(this).val() == 'Yes') {
$(appended).appendTo('body');
} else {
$(appended).remove();
}
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js"></script>
<input type="radio" id="postageyes" name="postage" value="Yes" />Yes
<input type="radio" id="postageno" name="postage" value="No" />No
JS 小提琴演示 http://jsfiddle.net/davidThomas/TcNEp/1/.
而且，进一步进行了温和的更新（因为我正在编辑以包含片段以及 JS Fiddle 链接），以便包装<input />元素与<label>s - 允许单击文本来更新相关内容<input />- 并更改创建要附加的内容的方式：
var appended = $('<div />', {
'id': 'appended',
'text': 'Appended content'
});
$('input:radio[name="postage"]').change(function() {
if ($(this).val() == 'Yes') {
$(appended).appendTo('body');
} else {
$(appended).remove();
}
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<label>
<input type="radio" id="postageyes" name="postage" value="Yes" />Yes</label>
<label>
<input type="radio" id="postageno" name="postage" value="No" />No</label>
JS 小提琴演示 http://jsfiddle.net/davidThomas/TcNEp/531/.
另外，如果您只需要根据用户检查的元素来显示内容，则可以进行轻微更新，使用显式显示/隐藏来切换可见性：
// caching a reference to the dependant/conditional content:
var conditionalContent = $('#conditional'),
// caching a reference to the group of inputs, since we're using that
// same group twice:
group = $('input[type=radio][name=postage]');
// binding the change event-handler:
group.change(function() {
// toggling the visibility of the conditionalContent, which will
// be shown if the assessment returns true and hidden otherwise:
conditionalContent.toggle(group.filter(':checked').val() === 'Yes');
// triggering the change event on the group, to appropriately show/hide
// the conditionalContent on page-load/DOM-ready:
}).change();
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<label>
<input type="radio" id="postageyes" name="postage" value="Yes" />Yes</label>
<label>
<input type="radio" id="postageno" name="postage" value="No" />No</label>
<div id="conditional">
<p>This should only show when the 'Yes' radio <input> element is checked.</p>
</div>
最后，仅使用 CSS：
/* setting the default of the conditionally-displayed content
to hidden: */
#conditional {
display: none;
}
/* if the #postageyes element is checked then the general sibling of
that element, with the id of 'conditional', will be shown: */
#postageyes:checked ~ #conditional {
display: block;
}
<!-- note that the <input> elements are now not wrapped in the <label> elements,
in order that the #conditional element is a (subsequent) sibling of the radio
<input> elements: -->
<input type="radio" id="postageyes" name="postage" value="Yes" />
<label for="postageyes">Yes</label>
<input type="radio" id="postageno" name="postage" value="No" />
<label for="postageno">No</label>
<div id="conditional">
<p>This should only show when the 'Yes' radio <input> element is checked.</p>
</div>
JS 小提琴演示 http://jsfiddle.net/davidThomas/TcNEp/532/.
参考：
- CSS:
-
:checked选择器 http://www.w3.org/TR/selectors/#checked.
- CSS 属性选择器。
-
一般兄弟姐妹（~) 组合器 http://www.w3.org/TR/selectors/#general-sibling-combinators.
- jQuery:
-
appendTo() http://api.jquery.com/appendTo/.
-
属性等于选择器 http://api.jquery.com/attribute-equals-selector/.
-
change() http://api.jquery.com/change/.
-
:checked选择器 http://api.jquery.com/checked-selector/.
-
filter() http://api.jquery.com/filter/.
-
is() http://api.jquery.com/is/.
-
:radio选择器 http://api.jquery.com/radio-selector/.
-
remove() http://api.jquery.com/remove/.
-
text() http://api.jquery.com/text/.
-
toggle() http://api.jquery.com/toggle/.
-
val() http://api.jquery.com/val/.
