js 實現二級聯動

onchange 事件

<body>
    <select id="province" onchange="func1()">
        <option value="shandong">山東</option>
        <option value="hebei">河北</option>
        <option value="beijing">北京</option>
    </select>

</body>
<script>
    function func1(){
        var pro = document.getElementById("province");
        console.log(pro.value)
    }
</script>

使用字典方式添加數據

一級數據顯示app

<body>
    <select id="province" >
    </select>

</body>
<script>
    data = {"廣東省":["廣州","佛山"],"北京":["海淀","廊坊"], "海南省":["三亞","海口"]};
    var pro = document.getElementById("province");
    for (var i in data){
        var option_pro = document.createElement("option");
        option_pro.innerHTML=i;
        pro.appendChild(option_pro);
    }
</script>

二級數據聯動方式一this

<body>
    <select id="province" onchange="func1(this)" >
    </select>
    <select id="city"></select>
</body>
<script>
    data = {"廣東省":["廣州","佛山"],"北京":["海淀","廊坊"], "海南省":["三亞","海口"]};
    var pro  = document.getElementById("province");
    var city = document.getElementById("city");

    for (var i in data){
        var option_pro = document.createElement("option");
        option_pro.innerHTML=i;
        pro.appendChild(option_pro);
    }

    function func1(self){
        //console.log((self.options[self.selectedIndex]).innerHTML);
        var choice = (self.options[self.selectedIndex]).innerHTML;

        var options = city.children;
        for (var k=0; k<options.length; k++){
            city.removeChild(options[k--]);
        }

        for (var i in data[choice]){
            var option_city = document.createElement("option");
            option_city.innerHTML = data[choice][i];
            city.appendChild(option_city);
        }
    }
</script>

二級數據聯動方式二spa

<body>
    <select id="province" onchange="func1(this)" >
    </select>
    <select id="city"></select>
</body>
<script>
    data = {"廣東省":["廣州","佛山"],"北京":["海淀","廊坊"], "海南省":["三亞","海口"]};
    var pro  = document.getElementById("province");
    var city = document.getElementById("city");


    for (var i in data){
        var option_pro = document.createElement("option");
        option_pro.innerHTML=i;
        pro.appendChild(option_pro);
    }



    function func1(self){
        //console.log((self.options[self.selectedIndex]).innerHTML);
        var choice = (self.options[self.selectedIndex]).innerHTML;

        city.options.length=0;

        for (var i in data[choice]){
            var option_city = document.createElement("option");
            option_city.innerHTML = data[choice][i];
            city.appendChild(option_city);
        }
    }
</script>