log4js-node/lib/appenders/logLevelFilter.js

"use strict";
var levels = require('../levels')
, debug = require('debug')('log4js:logLevelFilter')
, log4js = require('../log4js');

function logLevelFilter(allowedLevels, appender) {
  return function(logEvent) {
    debug("Checking ", logEvent.level, " against ", allowedLevels);
    if (allowedLevels.some(function(item) { return item.level === logEvent.level.level; })) {
      debug("Sending ", logEvent, " to appender ", appender);
      appender(logEvent);
    }
  };
}

function configure(config, appenderByName) {
  if (!Array.isArray(config.allow)) {
    throw new Error("No allowed log levels specified.");
  }

  var allowedLevels = config.allow.map(function(allowed) {
    var level = levels.toLevel(allowed);
    if (!level) {
      throw new Error("Unrecognised log level '" + allowed + "'.");
    }
    return level;
  });

  if (allowedLevels.length === 0) {
    throw new Error("No allowed log levels specified.");
  }

  if (!config.appender) {
    throw new Error("Missing an appender.");
  }

  return logLevelFilter(allowedLevels, appenderByName(config.appender));
}

exports.configure = configure;