chart.component.html

<div>
   <input 
      type="range" 
      min="500" max="50000" step="500"
      [ngModel]="dataLength"
      (ngModelChange)="modelChange($event)"
   />
   <div>
      <div
         *ngIf="!chart"
         #chartCanvas
         id="chartCanvas"
         [ngClass]="{ hidden: isLoading }"
      ></div>
      <canvas id="myChart" [ngClass]="{ hidden: isLoading }"> {{ chart }} </canvas>
  </div>
</div>