This simplistic sample Web Part demonstrates the use of JavaScript in a SharePoint Framework web part. The properties pane for this web part display a drop down list of lists in the current web. Once the user selects one of the lists, the web part display the contents of the list.
Open this sample in the gallery (popup panel): Open in gallery
Source: https://github.com/pnp/sp-dev-fx-webparts/tree/main/samples/js-display-list