【Angular】二级联动：如何从js二级联动，下拉框内容为动态查询

一、思路

①分别写两个各自独立的下拉框，互不影响；
②在父级下拉框里写一个ng-change方法，当父级下拉框的选中值变化时，调用方法；
③把父级选中的id或值传给子级下拉框，动态查询；

二、代码

1-1 html源码：

<label class="col-lg-1 control-label" for="major">专业</label>            <div class="col-lg-2">                <select   class="input-sm form-control" name="id" id="major"                                          ng-options="option.id as option.name for option in majorList"                                          ng-model="q.majorId" ng-change="professionChange()">                </select>            </div>            <label class="col-lg-1 control-label" for="position">岗位</label>            <div class="col-lg-2">                <select class="input-sm form-control" name="id" id="position"                        ng-options="option.id as option.name for option in positionList"                        ng-model="q.positionId">                </select>            </div>

1-2 html截图；

2-1js代码：

    /*专业初始化初始化：warn 必须初始化具体*/            $scope.majorList = [                { id:0 ,name:"1"}            ];            /*岗位初始化：position*/            $scope.positionList = [                { id:0 ,name:"2"}            ];        questionService.getMajorType().then(            function (res) {                /*清空*/                $scope.majorList = [];                for (var i = 0; i < res.data.length; i++) {                    /*初始化*/                    var majorSingleOption= {                        id:res.data[i].id,                        name: res.data[i].name                    };                    $scope.majorList.push(majorSingleOption);                }            }        );            /*当下拉选项变化的时候*/            $scope.professionChange=function () {                var index=document.getElementById("major").selectedIndex;//获取当前选择项的索引.                $scope.proChoosedId=document.getElementById("major").options[index].value;//获取当前选择项的值.                var num = $scope.proChoosedId.replace(/[^0-9]/ig,"");                questionService.getPositionType({professionId:num}).then(                    function (res) {                        $scope.positionList= [];                        for (var i = 0; i < res.data.length; i++) {                            /*初始化*/                            var positionSingleOption = {                                id:res.data[i].id,                                name: res.data[i].positionName                            };                            $scope.positionList.push(positionSingleOption);                        }                    }                );            };

2-2js截图

三、总结

①获取选中的父级下拉框内的id，通过改id来查询其子选项；

var index=document.getElementById("major").selectedIndex;//获取当前选择项的索引.                $scope.proChoosedId=document.getElementById("major").options[index].value;//获取当前选择项的值.

②从字符串中提取数字（正则）：

var num = $scope.proChoosedId.replace(/[^0-9]/ig,"");