将Angular 5.2升级到Angular 6，Bootstrap 4，jquery 3.3.1之后，Bootstrap 4下拉列表和Bootstrap-select下拉列表不再下降

更新：在进一步挖掘之后，我尝试了一个常规的bootstrap 4下拉列表，结果相同 . 下拉列表未打开 . 我相信这意味着它不能成为selectpicker类或bootstrap-select依赖项的问题 . 使用ng-bootstrap下拉列表时也会出现同样的问题 .

更新2：Ngx-dropdown确实有效，并且是我能找到的唯一可用的下拉列表，但它的运行方式不同 . 我希望这有助于找出原因 .

更新3：确认这不仅仅是在Chrome中工作时的问题 . firefox和safari中的问题相同 .

升级到Angular 6后，bootstrap-select元素不再下降，除非我删除class =“selectpicker” . 小的下拉箭头也不再出现 .

我已经尝试降级bootstrap selectpicker，升级到最新版本，检查jquery是否更新，确保selectpicker具有所需的依赖项和安装版本（我认为jquery大于1.8.1）

尝试手动强制下拉列表时，它也不起作用 . （见下文）

使用class =“selectpicker”

没有class = "selectpicker"

在更新到角度6并更新依赖关系（从 生产环境 中提取）之前

使用bootstrap-select和常规bootstrap 4下拉列表显示问题 .

通过按钮强制下拉：

使用ngx-select-dropdown工作：

用于给定选择选择器的代码：

<select class="selectpicker" ngDefaultControl name="selectTypes" (change)="onChangeTypes($event)" data-style="btn btn-danger btn-block"
                  title="Test Type">
                  <option *ngFor="let type of testTypes;  index as i" [attr.data-index]="i" value=i>{{type}}</option>
                </select>

init和再次刷新数据加载的代码

setTimeout(function() {
        if ($('.selectpicker').length !== 0) {
          $('.selectpicker').selectpicker({
            iconBase: 'ti',
            tickIcon: 'ti-check'
          });
        }

        $('.selectpicker').selectpicker('refresh');
      }, 100);

其他下拉列表的代码（常规下拉列表，bootstrap 4更新下拉列表，ngx下拉列表）

<div class="btn-group dropdown">
              <button type="button" (click)="dropdownToggle()" class="btn  btn-block btn-danger dropdown-toggle" data-toggle="dropdown"
                aria-haspopup="true" aria-expanded="false">
                Regular bootstrap 4 dropdown
              </button>
              <div class="dropdown-menu">
                <a class="dropdown-item" href="#">Action</a>
                <a class="dropdown-item" href="#">Another action</a>
                <a class="dropdown-item" href="#">Something else here</a>
                <div class="dropdown-divider"></div>
                <a class="dropdown-item" href="#">Separated link</a>
              </div>
            </div>

            <div class="dropdown">
              <a href="#" class="btn dropdown-toggle" data-toggle="dropdown">
                Regular
                <b class="caret"></b>
              </a>
              <ul class="dropdown-menu">
                <li><a href="#paper">Action</a></li>
                <li><a href="#paper">Another action</a></li>
                <li><a href="#paper">Something else here</a></li>
                <li class="divider"></li>
                <li><a href="#paper">Separated link</a></li>
                <li class="divider"></li>
                <li><a href="#paper">One more separated link</a></li>
              </ul>
            </div>
            

            <ngx-select-dropdown class="selectpicker dropdown btn-group btn-block dropdown-toggle btn btn-info" [multiple]="true" [config]="{height: auto, search:false}"
              [options]="['first', 'second', 'third']"></ngx-select-dropdown>

最后，package.json：

"dependencies": {
    "@angular/animations": "^6.1.4",
    "@angular/common": "^6.1.4",
    "@angular/compiler": "6.1.1",
    "@angular/core": "^6.1.4",
    "@angular/forms": "^6.1.4",
    "@angular/http": "^6.1.4",
    "@angular/platform-browser": "^6.1.4",
    "@angular/platform-browser-dynamic": "^6.1.4",
    "@angular/platform-server": "^6.1.4",
    "@angular/router": "^6.1.4",
    "@ng-bootstrap/ng-bootstrap": "^3.0.0",
    "@ngui/map": "0.30.3",
    "@sendgrid/mail": "^6.3.1",
    "@types/googlemaps": "3.30.11",
    "angular2-datetimepicker": "^1.1.1",
    "angularfire2": "^5.0.0-rc.3",
    "bootstrap": "4.1.3",
    "bootstrap-notify": "3.1.3",
    "bootstrap-select": "1.13.1",
    "bootstrap-switch": "3.3.4",
    "chart.js": "^2.7.2",
    "chart.piecelabel.js": "^0.15.0",
    "chartist": "0.11.0",
    "chartist-plugin-zoom": "0.4.1",
    "chartjs-plugin-zoom": "0.6.4",
    "core-js": "2.5.7",
    "datatables": "1.10.18",
    "datatables.net-bs": "1.10.19",
    "datatables.net-responsive": "2.2.3",
    "datatables.net-select": "^1.2.5",
    "datatables.net-select-bs": "^1.2.5",
    "easy-pie-chart": "2.1.7",
    "enhanced-resolve": "^4.1.0",
    "eonasdan-bootstrap-datetimepicker": "4.17.47",
    "firebase": "^5.4.0",
    "firebase-admin": "^6.0.0",
    "firebase-functions": "^2.0.5",
    "fullcalendar": "3.9.0",
    "jasny-bootstrap": "3.1.3",
    "jquery": "^3.3.1",
    "ng-circle-progress": "^1.2.0",
    "ng2-charts": "^1.6.0",
    "nodemailer": "^4.6.7",
    "nouislider": "11.1.0",
    "npm": "^6.0.1",
    "popper.js": "^1.14.3",
    "rxjs": "^6.2.2",
    "stripe": "^6.2.1",
    "twitter-bootstrap-wizard": "^1.2.0",
    "web-animations-js": "2.3.1",
    "xlsx": "^0.13.4",
    "zone.js": "0.8.26"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.7.0",
    "@angular/cli": "^6.1.5",
    "@angular/compiler-cli": "6.1.1",
    "@types/bootstrap": "4.1.2",
    "@types/chartist": "0.9.42",
    "@types/datatables.net-select": "^1.2.4",
    "@types/jasmine": "2.8.8",
    "@types/jquery": "3.3.6",
    "@types/node": "10.7.1",
    "codelyzer": "4.4.4",
    "jasmine-core": "3.2.1",
    "jasmine-spec-reporter": "4.2.1",
    "karma": "3.0.0",
    "karma-chrome-launcher": "2.2.0",
    "karma-cli": "1.0.1",
    "karma-coverage-istanbul-reporter": "2.0.1",
    "karma-jasmine": "1.1.2",
    "karma-jasmine-html-reporter": "1.3.1",
    "protractor": "5.4.0",
    "ts-node": "7.0.1",
    "tslint": "5.11.0",
    "typescript": ">=2.7.2 <2.10"
  },

我真的会帮助找出如何修复dropdown / selectpicker元素的任何帮助 . 具有讽刺意味的是，它是我们平台中使用最多的元素之一，升级到角度6之后它们都不起作用 .