url replacement

parse.js

export const NULL_PROTO = "file:/";

const isDefault = (x, y) =>
  !`${x}`.startsWith("file:") &&
  (!y || y === NULL_PROTO || !`${y}`.startsWith("file:"));

const filterString = (str, defaulted) =>
  defaulted ? str.replace(/^file:\/\//, "") : str;

class LooseURL extends URL {
  static NULL_PROTO = NULL_PROTO;
  constructor(uri, ref = NULL_PROTO) {
    let defaulted = isDefault(uri, ref);
    let parsed;
    try {
      parsed = new URL(uri, new URL(ref, NULL_PROTO));
    } catch {
      parsed = new URL("file://null");
      defaulted = true;
    }

    super(parsed.toString());
    this._defaulted = defaulted;
  }

  get protocol() {
    const t = super.protocol;
    return this._defaulted && t === "file:" ? null : t;
  }

  set protocol(scheme) {
    if (!this.host) {
      throw new Error("Setting protocol with no host... set host first.");
    }
    super.protocol = scheme;
  }

  get origin() {
    const base = super.origin;
    return this._defaulted && /^file:/.test(base) ? "null" : base;
  }

  toString() {
    return filterString(super.toString(), this._defaulted);
  }
}

export const parse = (uri, b) => new LooseURL(uri, b);