@discoveryjs/discovery/lib/core/utils/logger.js

Frontend framework for rapid data (JSON) analysis, shareable serverless reports and dashboards

const noopApi = new Proxy({}, { get: () => () => {
} });
const logLevels = ["silent", "error", "warn", "info", "perf", "debug"];
const logMethods = {
  error: ["error", "error"],
  warn: ["warn", "warn"],
  info: ["info", "info"],
  perf: ["log", "perf"],
  log: ["log", "any"],
  debug: ["debug", "debug"]
};
export class Logger {
  #logLevel;
  #prefix;
  #api;
  // stub methods
  error;
  warn;
  info;
  perf;
  debug;
  log;
  constructor(prefix = "", logLevel = "debug", consoleLikeApi = console) {
    this.#prefix = prefix;
    this.#api = consoleLikeApi || noopApi;
    this.logLevel = logLevel;
  }
  shouldLogLevel(logLevel) {
    const logLevelIndex = logLevels.indexOf(logLevel);
    return this.#logLevel !== "silent" && logLevelIndex !== -1 && logLevelIndex <= logLevels.indexOf(this.#logLevel);
  }
  get logLevel() {
    return this.#logLevel;
  }
  set logLevel(logLevel) {
    const levelIndex = logLevels.indexOf(logLevel);
    if (levelIndex === -1) {
      console.error(this.#prefix, `Bad log level "${logLevel}", supported: ${logLevels.join(", ")}`);
    }
    if (logLevel !== this.#logLevel) {
      const api = this.#api;
      const prefix = this.#prefix;
      const createApiMethodWrapper = (apiMethodName) => Function.prototype.bind.call(
        this.#api[apiMethodName],
        this.#api,
        ...this.#prefix ? [this.#prefix] : []
      );
      const createGroupMethod = (methodName, collapsed) => {
        return (message, content) => {
          const groupMethodName = collapsed ? "groupCollapsed" : "group";
          api[groupMethodName](`${prefix} ${message}`);
          const messages = typeof content === "function" ? content() : content;
          if (Array.isArray(messages)) {
            for (const entry of messages) {
              api[methodName](...Array.isArray(entry) ? entry : [entry]);
            }
          }
          api.groupEnd();
        };
      };
      this.#logLevel = logLevel;
      for (const [methodName, [apiMethod, level]] of Object.entries(logMethods)) {
        if (level === "any" || this.shouldLogLevel(level)) {
          this[methodName] = Object.assign(createApiMethodWrapper(apiMethod), {
            group: createGroupMethod(apiMethod, false),
            groupCollapsed: createGroupMethod(apiMethod, true)
          });
        } else {
          this[methodName] = Object.assign(() => {
          }, {
            group: () => () => {
            },
            groupCollapsed: () => () => {
            }
          });
        }
      }
    }
  }
}