test.js

var repl = require('repl');

function myEval(cmd, context, filename, callback) {
  callback(null, String(cmd));
}

const replServer = repl.start({
  prompt: '~> ',
  //eval: myEval
});

class TargetCollection extends Array {
    filter() {
        return new TargetCollection(...this);
    }
}

class Paguro {
    constructor() {
        this.targets = new TargetCollection();
        this.targets.push(1);
        this.targets.push(2);
        this.targets.push(3);
    }

    toString() {
        return '<Paguro>'
    }
}

const paguro = new Paguro();

replServer.context.paguro = paguro;