html

<div class="zsjm_one_one_one">
                <span class="zsjm_one_one_one_span">所在地區: </span>
                <div class="zsjm_one_one_one_one">
                    <select id="pro" class="lv_sid">
                        <option>請輸入您的省份</option>
                    </
 
select>
                </div>
                <div class="zsjm_one_one_one_one">
                    <select class="lv_sid" required id="city">
                        <option>請輸入您的市區</option>
 
                    </select>
                </div>
                <
 
div class="zsjm_one_one_one_one">
                    <select class="lv_sid" required id="county">
                        <option>請輸入您的縣區</option>
                    </select>
                </div>
            </div>

js

/** 頁面載入時 查省 */
        $.post(
            
 
"{:url('provice')}",
            {act: "pro"},
            function (msg) {
                // console.log(msg);
 
                var option = "<option>--請選擇--</option>";
                for (var i = 0; i < msg.length; i++) {
 
                    option += "<option value='" + msg[i]['id'] + "'>" + msg[i]['region_name'] + "</option>";
                }
                $("#pro").html(option);
            },
            'json'
        )
 
        /*省發生改變 查市*/
        $("#pro").change(function () {
 
            var pro_id = $("#pro option:selected").val();
 
            // $("#city").empty();
            $.post(
                "{:url('provice')}",
                {act: "city", id: pro_id},
                function (msg) {
 
                    var option = "<option>--請選擇--</option>";
                    for (var i = 0; i < msg.length; i++) {
 
                        option += "<option value='" + msg[i]['id'] + "'>" + msg[i]['region_name'] + "</option>";
                    }
                    $("#city").html(option);
                });
        })
 
 
        /*市發生改變 查縣*/
        $("#city").change(function () {
 
            var pro_id = $("#city option:selected").val();
 
            $.post(
                "{:url('provice')}",
                {act: "county", id: pro_id},
                function (msg) {
 
                    var option = "<option>--請選擇--</option>";
                    for (var i = 0; i < msg.length; i++) {
 
                        option += "<option value='" + msg[i]['id'] + "'>" + msg[i]['region_name'] + "</option>";
                    }
                    $("#county").html(option);
                });
        })

php

//省市縣三級聯動
    public function provice(){
        $act = input('post.');
 
        if($act['act'] == "pro"){
            $res = db('shopcity') -> where(['pid'=>0]) -> select();
        }else if($act['act'] == "city"){
 
            $res = db('shopcity') -> where(['pid'=>$act['id']]) -> select();
        }else if($act['act'] == "county"){
 
            $res = db('shopcity') -> where(['pid'=>$act['id']]) -> select();
        }
 
//        var_dump($res);die;
        return $res;
    }