persistable sclass JS is IF0<S>, Htmlable {
  S code;
  Set requiredLibraries;
  
  Set requiredLibraries() { ret requiredLibraries; }
  
  *(S code, O... dollarVars) {
    this.code = jsDollarVars(code, dollarVars);
  }
  
  public S get() { ret code; }
  
  toString { ret unnull(code); }
  
  void requireJQuery { require("jquery"); }
  
  void require(O library) {
    requiredLibraries = addToSet_create(requiredLibraries, library);
  }
  
  public S html() { ret hjs(code); }
}