Angular2 cli导入错误

Question

我正在尝试在Angular2项目中使用mdl-stepper。 在我的HTML中：

    <li class="mdl-step">
        <span class="mdl-step__label">
            <span class="mdl-step__title">
                <span class="mdl-step__title-text">Step 2</span>
            </span>
        </span>
        <div class="mdl-step__content">
            <h4>Step 2</h4>
        </div>
        <div class="mdl-step__actions">
            <button class="mdl-button mdl-js-button mdl-js-ripple-effect mdl-button--colored mdl-button--raised" data-stepper-next>
                Continue 
            </button>
            <button class="mdl-button mdl-js-button mdl-js-ripple-effect" data-stepper-cancel>
                Cancel
            </button>
            <button class="mdl-button mdl-js-button mdl-js-ripple-effect" data-stepper-back 
            (click)="onstepback($event)">
                Back
            </button>
        </div>
    </li>

在后退按钮上单击我正在发射一个事件。在home.component.ts onbackstep(){}内的var stepperElement = document.querySelector('ul.mdl-stepper'); var Stepper; Stepper = stepperElement.MaterialStepper; 文件中，我有以下内容：

Property 'MaterialStepper' does not exist on type 'Element'

它给我编译错误<form action="{{ url_for('mod_inst.addsrvtype') }}" method="post" class="sky-form"> <header>Add Package Template</header> <fieldset> <section> <label class="label">Template Name</label> <label class="input"> <input type="text" name="name" placeholder="Enter a name.. 3 Package Private Lesson, etc"> </label> <div class="note"><strong>Note:</strong> This is required, your students will not see this name.</div> </section> <div class="row"> <section class="col col-6"> <label class="label">Price</label> <label class="input"> <i class="icon-append fa fa-dollar"></i> <input type="text" name="price" value=""> </label> </section> <section class="col col-6"> <label class="label">Tax</label> <label class="input"> <i class="icon-append fa fa-percent"></i> <input type="text" name="tax" value=""> </label> </section> </div> <div class="row"> <button type="button" class="hideDiv">Unhide this row</button> <div class="hidden"> Hello <div class="row"> <button class="hideDiv">Unhide this row</button> <div class="hidden"> Hello <div class="row"> <button class="hideDiv">Unhide this row</button> <div class="hidden">Hello</div> </div> </div> </div> </div> </div> </fieldset> <footer> <button type="submit" class="button">Add Service</button> <button type="button" class="button button-secondary" onClick="window.history.back();">Cancel</button> </footer> <!-- END CONTENT --> </div><!-- END accordion CONTENT --> </div><!-- END accordion ITEM -->

我必须输入一些东西吗？

Answer 1

尝试使用 var stepperElement = document.querySelector（selector）;

它为我工作。现在没有错误。