Yes there is no change event for currently selected radio button. But problem is when each radio button is taken as a separate element. Instead a radio group should be considered a single element like select. So change event is triggered for that group. If it is a select element we never worry about each option in it, but take only the selected option. We store the current value in a variable which will become the previous value, when a new option is selected. Similarly you have to use a separate variable for storing value of checked radio button.

如果您想要识别前一个单选按钮，则必须循环鼠标按下事件。

var radios = document.getElementsByName("myRadios");
var val;
for(var i = 0; i < radios.length; i++){
    if(radios[i].checked){
        val = radios[i].value;
    }
}

请看这个:http://jsfiddle.net/diode/tywx6/2/

Yes there is no change event for currently selected radio button. But problem is when each radio button is taken as a separate element. Instead a radio group should be considered a single element like select. So change event is triggered for that group. If it is a select element we never worry about each option in it, but take only the selected option. We store the current value in a variable which will become the previous value, when a new option is selected. Similarly you have to use a separate variable for storing value of checked radio button.

如果您想要识别前一个单选按钮，则必须循环鼠标按下事件。

var radios = document.getElementsByName("myRadios");
var val;
for(var i = 0; i < radios.length; i++){
    if(radios[i].checked){
        val = radios[i].value;
    }
}

请看这个:http://jsfiddle.net/diode/tywx6/2/

博士Tl;

'focusout'在'change'事件之前被分派-示例:

const radioName = 'radio';

// Add radios
document.body.innerHTML = `
<style>
input + label {
  margin-left: 1rem;
}
</style>
<form action="#" name="example-form">
  <fieldset>
    ${Array(5).fill(null, 0, 5).map((_, i) => {
        const offsetId = i + 1;
        const id = `radio-${offsetId}`;
        return `<label for="${id}">Radio ${offsetId}</label>
        <input type="radio" name="${radioName}" id="${id}" value="${offsetId}" />`;
      }).join('\n')}
  </fieldset>
</form>
`;

const {log} = console,

    form = document.forms['example-form']; 

form.addEventListener('submit', e => e.preventDefault());

form.addEventListener('change', e => {
    const {target} = e;
    if (target.matches(`[type="radio"][name="${radioName}"]`)) {
        log(`[${e.type}]: "${target.id}" selected;  Value: ${target.value}`);
    }
});

form.addEventListener('focusout', e => {
    const {target} = e,

        soonToBePrevValue = target && target.form ? 
            target.form.elements[radioName].value : null;
    
    if (!target.matches(`[type="radio"][name="${radioName}"]`) || !soonToBePrevValue) {
        return;
    }

    // value, for '[name="radio"]', contained in form, will change after 'focusout' event
    // has completed it's bubbling stage.
    log(`[${e.type}]: previously selected radio value: ` + 
        `${soonToBePrevValue}`);
        
    // log("Soon to be \"previous\" radio: ", target);
});

斯菲德尔

除了存储之前的状态，我不认为还有其他方法。 下面是使用jQuery的解决方案

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script> 
<script type="text/javascript">
    var lastSelected;
    $(function () {
        //if you have any radio selected by default
        lastSelected = $('[name="myRadios"]:checked').val();
    });
    $(document).on('click', '[name="myRadios"]', function () {
        if (lastSelected != $(this).val() && typeof lastSelected != "undefined") {
            alert("radio box with value " + $('[name="myRadios"][value="' + lastSelected + '"]').val() + " was deselected");
        }
        lastSelected = $(this).val();
    });
</script>

<input type="radio" name="myRadios" value="1" />
<input type="radio" name="myRadios" value="2" />
<input type="radio" name="myRadios" value="3" />
<input type="radio" name="myRadios" value="4" />
<input type="radio" name="myRadios" value="5" />

在考虑了一会儿之后，我决定去掉变量并添加/删除类。这是我得到的:http://jsfiddle.net/BeQh3/2/

如何使用Jquery的变化事件?

$(function() {
    $('input:radio[name="myRadios"]').change(function() {
        if ($(this).val() == '1') {
            alert("You selected the first option and deselected the second one");
        } else {
            alert("You selected the second option and deselected the first one");
        }
    });
});

jsfiddle: http://jsfiddle.net/f8233x20/

This is just off the top of my head, but you could do an onClick event for each radio button, give them all different IDs, and then make a for loop in the event to go through each radio button in the group and find which is was checked by looking at the 'checked' attribute. The id of the checked one would be stored as a variable, but you might want to use a temp variable first to make sure that the value of that variable changed, since the click event would fire whether or not a new radio button was checked.