Check whether specific radio button is checked

问题

I'm having trouble after looking at the jQuery docs. I'm just trying to return true/false in one my my jquery methods depending on the check of a certain radiobutton and if it's selected or not

I've tried several things but have not been able to get this right:

<input type="radio" runat="server" name="testGroup" id="test1" /><label for="<%=test1.ClientID %>" style="cursor:hand" runat="server">Test1</label>
<input type="radio" runat="server" name="testGroup" id="test2" /><label for="<%=test2.ClientID %>" style="cursor:hand" runat="server">Test2</label>
<input type="radio" runat="server" name="testGroup" id="test3" /> <label for="<%=test3.ClientID %>" style="cursor:hand">Test3</label>

and in my method I have this:

return $("input[@name='test2']:checked");

I'm getting an undefined on $("input[@name='test2']:checked");

UPDATED:

example:

<input type="radio" runat="server" name="radioGroup"  id="payPalRadioButton" value="paypalSelected" /> 

this returns 'undefined' still:

$("input[@name=radioGroup]:checked").attr('payPalRadioButton'); 

If I try this, I get 'false' even if I select the radio button:

$('input:radio[name=radioGroup]:checked').val() == 'paypalSelected'

回答1:

Your selector won't select the input field, and if it did it would return a jQuery object. Try this:

$('#test2').is(':checked'); 

回答2:

I think you're using the wrong approach. You should set the value attribute of your input elements. Check the docs for .val() for examples of setting and returning the .val() of input elements.

ie.

<input type="radio" runat="server" name="testGroup" value="test2" />

return $('input:radio[name=testGroup]:checked').val() == 'test2';

回答3:

1.You don't need the @ prefix for attribute names any more:

http://api.jquery.com/category/selectors/attribute-selectors/:

Note: In jQuery 1.3 [@attr] style selectors were removed (they were previously deprecated in jQuery 1.2). Simply remove the ‘@’ symbol from your selectors in order to make them work again.

2.Your selector queries radio buttons by name, but that attribute is not defined in your HTML structure.

回答4:

You should remove the '@' before 'name'; it's not needed anymore (for current jQuery versions).

You're want to return all checked elements with name 'test2', but you don't have any elements with that name, you're using an id of 'test2'.

If you're going to use IDs, just try:

return $('#test2').attr('checked');

回答5:

WHy bother with all of the fancy selectors? If you're using those id="" attributes properly, then 'test2' must be the only tag with that id on the page, then the .checked boolean property will tell you if it's checked or not:

if ($('test2').checked) {
    ....
}

You've also not set any values for those radio buttons, so no matter which button you select, you'll just get a blank "testGroup=" submitted to the server.

回答6:

$("input[@name='<%=test2.ClientID%>']:checked");

use this and here ClientID fetch random id created by .net.

回答7:

Just found a proper working solution for other guys,

// Returns true or false based on the radio button checked
$('#test1').prop('checked')


$('body').on('change','input[type="radio"]',function () {
alert('Test1 checked = ' + $('#test1').prop('checked') + '. Test2 checked = ' + $('#test2').prop('checked') + '. Test3 checked = ' + $('#test3').prop('checked'));
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<input type="radio" runat="server" name="testGroup" id="test1" /><label for="<%=test1.ClientID %>" style="cursor:hand" runat="server">Test1</label>

<input type="radio" runat="server" name="testGroup" id="test2" /><label for="<%=test2.ClientID %>" style="cursor:hand" runat="server">Test2</label>

<input type="radio" runat="server" name="testGroup" id="test3" /> <label for="<%=test3.ClientID %>" style="cursor:hand">Test3</label>

and in your method you can use like

return $('#test2').prop('checked');

来源：https://stackoverflow.com/questions/2195125/check-whether-specific-radio-button-is-checked