access scope in liquidjs filter

HTML

<script src="https://cdn.jsdelivr.net/npm/liquidjs/dist/liquid.browser.min.js"></script>
<div id="log"></div>

JavaScript

const { Liquid } = liquidjs
const engine = new Liquid()
engine.registerTag('random', {
	parse(tagToken) {
  	this.args = tagToken.args.split(' ')
  },
  render(context, emitter) {
  	const index = Math.floor(this.args.length * Math.random())
  	emitter.write(this.args[index])
  }
})

const tpl = `{% random foo bar coo %}`
const html = engine.parseAndRenderSync(tpl)
log(html)

function log(text) {
   document.querySelector("#log").innerText += text + '\n';
}