'Node.js Command Line Console Log Level

How do you set the log level for node when starting it from the command line? I admit, i'm a node.js newbie, but looking for something like node myapp.js --loglevel warn

node.jscommand-line-arguments


Solution 1:[1]

Not possibly quite what you are after but you can enable debugging within node by setting a NODE_DEBUG environment variable first.

E.g. export NODE_DEBUG="net" && node myapp.js will give debugging for network related node operations.

https://github.com/joyent/node/blob/master/lib/net.js#L66

Solution 2:[2]

You can overwrite the console.log,console.debug,console.error,console.warn functions to allow logLevels.

Check out my snippet written in typescript:

export type LogLevel = "debug" | "log" | "warn" | "error" | "none";
let logLevels = ["debug", "log", "warn", "error", "none"];
let shouldLog = (level: LogLevel) => {
  // @ts-ignore
  return logLevels.indexOf(level) >= logLevels.indexOf(global.logLevel);
};

// @ts-ignore
global.logLevel = "debug";
let _console=console
global.console = {
  ...global.console,
  log: (message?: any, ...optionalParams: any[]) => {
    shouldLog("log")&&_console.log(message, ...optionalParams);
  },
  warn: (message?: any, ...optionalParams: any[]) => {
    shouldLog("warn") && _console.warn(message, ...optionalParams);
  },
  error: (message?: any, ...optionalParams: any[]) => {
    shouldLog("error") && _console.error(message, ...optionalParams);
  },
  debug: (message?: any, ...optionalParams: any[]) => {
    shouldLog("debug") && _console.debug(message, ...optionalParams);
  },
};

Then you can use the console functions as usual and set the logLevel with globals.logLevel="warn",...

Sources

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Source: Stack Overflow

Solution Source
Solution 1 AndyA
Solution 2 haschtl

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