This is how I have mine set up .. if it helps you.

assets/vendor/vega_lite.js

/* import vegaEmbed from "vega-embed"; */

/**
 * A hook used to render graphics according to the given
 * Vega-Lite specification.
 *
 * The hook expects a `vega_lite:<id>:init` event with `{ spec }` payload,
 * where `spec` is the graphic definition as an object.
 *
 * Configuration:
 *
 *   * `data-id` - plot id
 * 
 * 
 * OPTIONS : FULL LIST @ https://github.com/vega/vega-embed#options
 * Eg,
 * actions:	Boolean / Object	
 * Determines if action links ("Export as PNG/SVG", "View Source", "View Vega" 
 * (only for Vega-Lite), "Open in Vega Editor") are included with the embedded view. If the value is true, 
 * all action links will be shown and none if the value is false. This property can take a key-value mapping 
 * object that maps keys (export, source, compiled, editor) to boolean values for determining if each action 
 * link should be shown. By default, export, source, and editor are true and compiled is false. These defaults 
 * can be overridden: for example, if actions is {export: false, source: true}, the embedded visualization 
 * will have two links – "View Source" and "Open in Vega Editor". The export property can take a key-value 
 * mapping object that maps keys (svg, png) to boolean values for determining if each export action 
 * link should be shown. By default, svg and png are true.
 */


const VegaLite = {
  mounted() {
    this.id = this.el.getAttribute("data-id");
    this.viewPromise = null;

    const container = document.createElement("div");
    this.el.appendChild(container);

    this.handleEvent(`vega_lite:${this.id}:init`, ({ spec }) => {
      this.viewPromise = vegaEmbed(container, spec, {"actions": false})
        .then((result) => result.view)
        .catch((error) => {
          console.error(
            `Failed to render the given Vega-Lite specification, got the following error:\n\n    ${error.message}\n\nMake sure to check for typos.`
          );
        });
    });
  },

  destroyed() {
    if (this.viewPromise) {
      this.viewPromise.then((view) => view.finalize());
    }
  },
};

export default VegaLite;

assets/js/app.js

import VegaLite from '../vendor/vega_lite';

...

Hooks.VegaLite = VegaLite;

mix.exs

      {:vega_lite, "~> 0.1.2"},