Need help importing NodeJS-Module "htmlparser2" in SmartMobileStudio

Question

I tried to use the htmlparser2 module (installed via npm install htmlparser2) in SmartMobileStudio. The module itself works well in direct javascript (using a slightly changed sample from htmlparser2's Homepage):

var htmlparser = require("htmlparser2");
var parser = new htmlparser.Parser({
    onopentag: function(name, attribs){
        console.log(name);
        console.log(attribs);
    }
});
parser.write("<img src='image1.jpg'>");
parser.end();

Using SMS (2.0.0.9 Beta) I tried to import the module like this:

unit NodeJS.htmlparser2;

interface

uses
  NodeJS.Core,
  NodeJS.events;

type
  TOnTag = procedure(name: string; attribs: Variant);
  TOnText = procedure(text: string);

  JParser = class external(NodeJS.events.JNodeEventEmitter)
    procedure write(s: string);
    procedure &end;
  end;

  Jhtmlparser_Exports = class external
  public
    function Parser(onopentag: TOnTag; ontext: TOnText; onclosetag: TOnTag): JParser;
  end;

function htmlparser2: Jhtmlparser_Exports;

implementation

function htmlparser2: Jhtmlparser_Exports;
begin
  result := Jhtmlparser_Exports( require("htmlparser2") );
end;

end.

I changed the project generated by the Node.js-New-Project-Template like this:

[...]

procedure TServer.Run;
begin
  var htmlparser := NodeJS.htmlparser2.htmlparser2;

  var parser := htmlparser.Parser(
   procedure (Name: string; Attribs: Variant)
   begin
     console_.log([Name]);
     console_.log([Attribs]);
   end,
   nil,
   nil);

  parser.write("<img src='image1.jpg'>");
  parser.end();
end;

The Problem is that the emitted code is not correct, but nearly:

[...]
parser = htmlparser.Parser(function (Name$3, Attribs) {
   console_().log([Name$3].slice());
   console_().log([Attribs].slice());
},null,null);
[...]

This works:

[...]
parser = new htmlparser.Parser({onopentag: function (Name$3, Attribs) {
   console_().log([Name$3].slice());
   console_().log([Attribs].slice());
}});
[...]

The difference is the "new" keyword and the named event callback "onopentag". What do I need to write to generate working js code?

Answer 1

Because a class can't be "exported" in pascal like you can with javascript and requirejs/nodejs, we need to use an external class trick: we can set some code for the external class name. Second, we need to supply an "options" object (more verbose but needed for type safety).

JParserOptions = class
  onopentag : TOnTag;
  ontext    : TOnText;
  onclosetag: TOnTag
end;

JParser = class external '(htmlparser2()).Parser' (NodeJS.events.JNodeEventEmitter)
  constructor Create(options: JParserOptions);

  procedure write(s: string);
  procedure &end;
end;

We can use this as follows:

var options = JParserOptions.Create;
options.onopentag := procedure (Name: string; Attribs: Variant)
  begin
    console_.log([Name]);
    console_.log([Attribs]);
  end;

var parser := new JParser(options);

Answer 2

By the way, I found a better solution: use a class reference (JParserClass = class of JParser)

  JParser = class external(NodeJS.events.JNodeEventEmitter)
    constructor Create(onopentag: TOnTag; ontext: TOnText; onclosetag: TOnTag);
    procedure write(s: string);
    procedure &end;
  end;
  JParserClass = class of JParser;

  Jhtmlparser_Exports = class external
  public
    Parser: JParserClass;
  end;

Then you can create the class like this:

  var parser := new (htmlparser2.Parser)(

Or like this:

  var parserclass = htmlparser2.Parser;
  var parser := new parserclass(

Or:

  var parserclass = htmlparser2.Parser;
  var parser := parserclass.Create(