Connection.ts

declare type DataReceived = (data: any) => void;

class Connection {
	constructor() {
	let thisHubConnection = this;
        this.dataReceived = data => {
	    this.log(data);
            thisHubConnection.log(data);
        };

	this.dataReceived("foo");
	}
	
	private dataReceived : DataReceived

	private log(data: any) {
	    console.log(data);
	}
}

let bar = new Connection();

gistfile1.txt

var Connection = (function () {
    function Connection() {
        var _this = this;
        var thisHubConnection = this;
        this.dataReceived = function (data) {
            _this.log(data);
            thisHubConnection.log(data);
        };
        this.dataReceived("foo");
    }
    Connection.prototype.log = function (data) {
        console.log(data);
    };
    return Connection;
}());
var bar = new Connection();