var rad = document. myform . mybroadcasts; Var prev = null; For (var I = 0;I < rad.length;我+ +){ rad[我]。addEventListener('change'， function() { (上一页)?console.log (prev.value):空; If (this !== prev) { Prev = this; ｝ console.log (this.value) })； ｝ <表单名称= " myForm " > <input type="radio" name=" mybroadcasts " value="1" /> <input type="radio" name=" mybroadcasts " value="2" /> > < /形式

下面是一个JSFiddle演示:https://jsfiddle.net/crp6em1z/

我想做两点改变:

<input type="radio" name="myRadios" onclick="handleClick(this);" value="1" />
<input type="radio" name="myRadios" onclick="handleClick(this);" value="2" />

使用onclick处理程序而不是onchange -您正在更改无线电输入的“已检查状态”，而不是值，因此不会发生更改事件。 使用单个函数，并将其作为参数传递，这将便于检查当前选择的值。

ETA:除了handleClick()函数，您还可以在页面作用域变量中跟踪收音机的原始/旧值。那就是:

var currentValue = 0;
function handleClick(myRadio) {
    alert('Old value: ' + currentValue);
    alert('New value: ' + myRadio.value);
    currentValue = myRadio.value;
}

var currentValue = 0; 函数handleClick(myRadio) { alert('旧值:' + currentValue); alert('新值:' + myRadio.value); currentValue = myRadio.value; ｝ <input type="radio" name=" my" onclick="handleClick(this);" value="1" /> . <input type="radio" name=" my" onclick="handleClick(this);" value="2" /> .

将之前选中的radio存储在一个变量中: http://jsfiddle.net/dsbonev/C5S4B/

HTML

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

JS

var changeHandler = (function initChangeHandler() {
    var previousCheckedRadio = null;

    var result = function (event) {
        var currentCheckedRadio = event.target;
        var name = currentCheckedRadio.name;

        if (name !== 'myRadios') return;

        //using radio elements previousCheckedRadio and currentCheckedRadio

        //storing radio element for using in future 'change' event handler
        previousCheckedRadio = currentCheckedRadio;
    };

    return result;
})();

document.addEventListener('change', changeHandler, false);

Js示例代码

var changeHandler = (function initChangeHandler() {
    var previousCheckedRadio = null;

    function logInfo(info) {
        if (!console || !console.log) return;

        console.log(info);
    }

    function logPrevious(element) {
        if (!element) return;

        var message = element.value + ' was unchecked';

        logInfo(message);
    }

    function logCurrent(element) {
        if (!element) return;

        var message = element.value + ' is checked';

        logInfo(message);
    }

    var result = function (event) {
        var currentCheckedRadio = event.target;
        var name = currentCheckedRadio.name;

        if (name !== 'myRadios') return;

        logPrevious(previousCheckedRadio);
        logCurrent(currentCheckedRadio);

        previousCheckedRadio = currentCheckedRadio;
    };

    return result;
})();

document.addEventListener('change', changeHandler, false);

您可以添加以下JS脚本

<script>
    function myfunction(event) {
        alert('Checked radio with ID = ' + event.target.id);
    }
    document.querySelectorAll("input[name='myRadios']").forEach((input) => {
        input.addEventListener('change', myfunction);
    });
</script>

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/

如图所示: http://www.w3schools.com/jsref/event_onchange.asp 单选按钮不支持onchange属性。

您链接的第一个SO问题给出了答案:使用onclick事件，并检查它触发的函数内部的单选按钮状态。