javascript - 其他组合框的组合框更改值

Question

我在一个表单上有两个组合框。每个都有值 Yes 和 No。我想要的是当一个改变时另一个得到相反的结果(如果第一个是 Yes 另一个是 No)。我需要用 Javascript 来完成。我看到了这个问题How to change "selected" value in combobox using JavaScript?但它只应用于一个组合框。

我该怎么做？

LE: 我需要这个例子来制作组合框。我不能使用单选按钮

Answer 1

我创建了一个简单的 jsFiddle Demo .这并不完美，只是说明了这个想法。

HTML:

<select id="first">
    <option value="0" selected>No</option>
    <option value="1">Yes</option>
</select>

<select id="second">
    <option value="0">No</option>
    <option value="1" selected>Yes</option>
</select>

Javascript:

//find the selects in the DOM
var first = document.getElementById('first');
var second = document.getElementById('second');

//this is the handler function we will run when change event occurs
var handler = function () {
    //inside the handler, "this" should be the select 
    //whose change event we are currently handling

    //get the current value and invert it (0 -> 1, 1 -> 0)
    var invertedValue = this.value === '0' ? 1 : 0;

    //check which select's change we are currently handling
    //and set the inverted value as the other select's value
    if (this === first) {
        second.value = invertedValue;
    } else {
        first.value = invertedValue;
    }

};

//add handler function to run on change event on both selects
first.addEventListener('change', handler, false);
second.addEventListener('change', handler, false);