.attr('checked','checked') does not work_问答_开发者

.attr('checked','checked') does not work

开发者 https://www.devze.com 2023-02-16 00:17 出处：网络

I am trying to check radio. Neither the following works: [edit] $(\'selector\').attr(\'checked\',\'checked\');

相关专题：jquery

I am trying to check radio. Neither the following works:

[edit]

$('selector').attr('checked','checked');
$('selector').attr('checked',true);

The two alert() in the following code show "1" and "a", respectively. My expectation is the second alert() showing "b".

Opera does check the second radio box in its browser, but its element inspector, dragonfly, shows that the DOM is not changed.

[end edit]

I had read the FAQ before I posted this question:

http://docs.jquery.com/Frequently_Asked_Questions#How_do_I_check.2Funcheck_a_checkbox_input_or_radio_button.3F

Helps will be much appreciated!

TIA

The xhtml page and code follows:

<!DOCTYPE html 
     PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
     "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>Weird Behavior</title>
<script type="text/javascript" src="scripts/jquery.js"/>
<script type="text/javascript">
function clickme(){
    alert($('input[name="myname"][value="b"]').length);
    $('input[name="myname"][value="b"]').attr('checked','checked');
    $('#b').attr('checked',true);
    alert($('input[name="myname"][checked]').val());
};
</script>
</head>
<body>
    <form action="">
        <fieldset>
            <legend>Why 开发者_开发问答check is not switched?</legend>
            <input type="radio" name="myname" value="a" id="a" checked="checked"/>A
            <input type="radio" name="myname" value="b" id="b"/>B
        </fieldset>
    </form>
    <p>
    <button type="button" onclick="clickme()">click me</button>
    </p>
</body>
</html>

 $('.checkbox').attr('checked',true);

will not work with from jQuery 1.6.

Instead use

$('.checkbox').prop('checked',true);
$('.checkbox').prop('checked',false);

Full explanation / examples and demo can be found in the jQuery API Documentation https://api.jquery.com/attr/

With jQuery, never use inline onclick javascript. Keep it unobtrusive. Do this instead, and remove the onclick completely.

Also, note the use of the :checked pseudo selector in the last line. The reason for this is because once the page is loaded, the html and the actual state of the form element can be different. Open a web inspector and you can click on the other radio button and the HTML will still show the first one is checked. The :checked selector instead filters elements that are actually checked, regardless of what the html started as.

$('button').click(function() {
    alert($('input[name="myname"][value="b"]').length);
    $('input[name="myname"][value="b"]').attr('checked','checked');
    $('#b').attr('checked',true);
    alert($('input[name="myname"]:checked').val());
});

http://jsfiddle.net/uL545/1/

$('.checkbox').prop('checked',true); 
$('.checkbox').prop('checked',false);

... works perfectly with jquery1.9.1

Why not try IS?

$('selector').is(':checked') /* result true or false */

Look a FAQ: jQuery .is() enjoin us ;-)

$("input:radio").attr("checked",true); //for all radio inputs

$("your id or class here").attr("checked",true); //for unique radios

equally the same works for ("checked","checked")

I don't think you can call

$.attr('checked',true);

because there is no element selector in the first place. $ must be followed by $('selector_name'). GOod luck!

It works, but

$('input[name="myname"][checked]').val()

will return the value of the first element with attribute checked. And the a radio button still has this attribute (and it comes before the b button). Selecting b does not remove the checked attribute from a.

You can use jQuery's :checked: