Create logger module. Refs matrix-org#332

Signed-off-by: André Jaenisch <andre.jaenisch@posteo.de>

src/logger.js

@@ -0,0 +1,21 @@
+"use strict";
+/**
+ * @module logger
+ */
+const log = require("loglevel");
+
+// This is to demonstrate, that you can use any namespace you want.
+// Namespaces allow you to turn on/off the logging for specific parts of the
+// application.
+// An idea would be to control this via an environment variable (on Node.js).
+// See https://www.npmjs.com/package/debug to see how this could be implemented
+// Part of #332 is introducing a logging library in the first place.
+const DEFAULT_NAME_SPACE = "matrix";
+const logger = log.getLogger(DEFAULT_NAME_SPACE);
+log.setDefaultLevel(log.levels.WARN);
+
+/**
+ * Drop-in replacement for <code>console</code> using {@link https://www.npmjs.com/package/loglevel|loglevel}.
+ * Can be tailored down to specific use cases if needed.
+*/
+module.exports.logger = logger;