$ npm i -S log4js @types/log4js

import { configure, getLogger } from "log4js";

configure({
  appenders: {
    console: {
      type: "console"
    },
    logfile: { type: "file", filename: "log/app.log" }
  },
  categories: { default: { appenders: ["console", "logfile"], level: "error" } }
});

const logger = getLogger();

logger.level = "debug";
logger.debug("Some debug messages");
logger.error("aha!");

[2019-10-20T10:58:43.835] [DEBUG] default - Some debug messages
[2019-10-20T10:58:43.839] [ERROR] default - aha!