AsURLAsset.js

const path = require('path');
const Asset = require('parcel-bundler/src/Asset');
const urlJoin = require("parcel-bundler/src/utils/urlJoin");

class AsURLAsset extends Asset {
    constructor(filename, options) {
        super(filename, options);
        this.type = "as-url";
        const { dir, name } = path.parse(filename);
        this.srcName = name;
        this.srcDir = path.relative(options.rootDir, dir);
        this.dst = null;
    };

    // The default `getDependencies` checks to see if this asset has
    // any contents before collecting dependencies - but, as it's
    // entirely virtual, we fail that test.
    async getDependencies() {
        await this.collectDependencies();
    }

    collectDependencies() {
        // The .as-url asset is in the same directory as the target
        // asset. So, just import it as a local dependency. The return
        // value of addURLDependency is a hash that gets
        // post-processed into a relative-to-root path, so anchor it
        // to the public URL.
        this.dst = urlJoin(
            this.options.publicURL,
            this.addURLDependency(path.join(".", this.srcName)),
        );
    };

    generate() {
        const code = `export default ${JSON.stringify(this.dst)};`;
        return [
            {
                type: "js",
                value: code,
            }
        ];
    };
};

module.exports = AsURLAsset;