ngSubmit以Angular 2格式刷新页面

当我点击按钮，页面刷新。

我的验证工作正常。

当用户点击按钮时，如何才能停止页面刷新？

以下是我使用的HTML：

<div class="panel panel-default">
    <div class="panel-heading">
        <h3 class="panel-title">Add Employee</h3>
        {{model | json}}
        {{EName.errors | json}}
    </div>
    <div class="panel-body">  
        <form (ngSubmit)="onSubmit(empForm)" #empForm="ngForm" autocomplete="off" novalidate>

        <div class="form-group">
            <label for="EmployeeName">Employee Name</label>
            <input type="text" class="form-control" id="EmployeeName" placeholder="Employee Name" required [(ngModel)]="model.EName" name="EName" #EName="ngModel" ngControl="Ename" #EName="EName" >
            <div *ngIf="EName.touched && EName.errors" >
                <div *ngIf="EName.errors.required"  class="alert alert-danger">
                    Employee Name is required
                </div>
            </div>
        </div>
        <div class="form-group">
            <label for="Age">Age</label>
            <input type="text" class="form-control" id="Age" name="Age" placeholder="Age" [(ngModel)]="model.Age" ngControl="Age">
        </div>
        <div class="form-group">            
            <label for="Sex">Sex</label>
            <div class="d-block">
                <label class="radio-inline">
                    <input type="radio" name="sex" id="Male" value="0" (click)="model.Sex=$event.target.value"> Male
                </label>
                <label class="radio-inline">
                    <input type="radio" name="sex" id="Female" value="1" (click)="model.Sex=$event.target.value"> Female
                </label>
            </div>
        </div>

        <div class="form-group">
            <label for="DOJ">Date of Joining</label>
            <datepicker [(ngModel)]="model.DOJ" name="DOJ"></datepicker>
        </div>

        <div class="form-group">
            <label for="Salary">Salary</label>
            <input type="text" class="form-control" id="Salary" placeholder="Salary" [(ngModel)]="model.Salary" name="Salary">
        </div>

        <div class="form-group">
            <label for="Designation">Designation</label>
            <select id="Designation" name="designation" class="form-control" required [(ngModel)]="model.Designation" name="designation" #desig="ngForm" ngControl="Designation">
                <option value="" selected>-- Select  --</option>
                <option *ngFor="let designation of designations" value="{{ designation.id }}"> 
                    {{designation.name}} 
                </option>
            </select>
            <div [hidden]="desig.valid || desig.pristine" class="alert alert-danger">
                Please select a proper designation.
            </div>
        </div>
        <button type="submit" class="btn btn-default" [disabled] ="!empForm.form.valid">Submit</button>
        </form>
    </div>
</div>