Why when I use cytoscape in angular 7 there is a undefined error

Question

I am setting up angular and Cytoscape. When I initialized the node and edge, there is this error.

//ts file

import * as $ from 'jquery';
declare var cytoscape: any;
...
  cy = cytoscape({
    container: $('#cy')
    ...})

//html
<div id="cy">

</div>