点击后如何检查单选按钮是否已被检查？

Question

I have a click listener on my radiobuttons.

I need to check whether a radiobutton was already checked prior to the click, or if it wasnt.

$('.GridRadio').live('click', function () {
    alert($(this).is(':checked'));
});

However, the above alerts true every time. How can i see if it was checked already, prior to when being clicked?

Answer 1

You could use data() to store the previous value of the radio, and then check the current value against that:

$(".GridRadio").click(function() {
    var lastValue = $(this).data("last-value");
    var value = $(this).val();

    if (lastValue == value) {
        alert("Already checked");
    }
    else {
        alert("Not previously checked");
    }

    $(".GridRadio").data("last-value", "");
    $(this).data("last-value", value);
});

Example fiddle

If you set the checked attribute on one of the radios in HTML on page load, add this code to set the data for that specific one:

$(".GridRadio:checked").data("last-value", $(".GridRadio:checked").val())

Answer 2

If you're using live you probably append $('.GridRadio') after $(document).ready . if that's right - you can do this check when you append it. then when it is being clicked - it will always be the negative value.

(and if it is in the page from the beginning - you can do this check once the page is reloaded, before someone clicks on it.)