If you really need jQuery to do something so simple like Windy Plugin, maybe you should consider programming something else
This is very complex example placing your plugin element inside Leaflet map on desktop, and in different location on mobile.
When mounted to the page, your plugin contains some handy shortcuts to DOM elements inside your plugin. this.node contains el of your plugin, and for example this.refs.graph contains el with data-ref="graph" attribute.
Module $ can also act as shortcut to document.querySelector, so for instance $('.closing-x', this.node ) will return el of closing button.
As you can see dependencies can contain list of external libraries, that will be loaded before your plugin is even mounted to the page.
attachPoint contains selector of el, where your plugin will be mounted to the page.
Whenever your plugin is opened from contextmenu hook, this.onopen method receives { lat, lon } object with required coordinates.
See Windy Plugins API to have better idea how plugin system works or Windy API documentation