log4js-node/docs/recording.md

Recording Appender

This appender stores the log events in memory. It is mainly useful for testing (see the tests for the category filter, for instance).

Configuration

• type - recording
• maxLength - integer (optional, defaults to undefined) - the maximum array length for the recording. If not specified, the array will grow until cleared

There is no other configuration for this appender.

Usage

The array that stores log events is shared across all recording appender instances, and is accessible from the recording module. require('<LOG4JS LIB DIR>/appenders/recording') returns a module with the following functions exported:

• replay - returns Array<LogEvent> - get all the events recorded.
• playback - synonym for replay
• reset - clears the array of events recorded.
• erase - synonyms for reset

Example

const recording = require("log4js/lib/appenders/recording");
const log4js = require("log4js");
log4js.configure({
  appenders: { vcr: { type: "recording" } },
  categories: { default: { appenders: ["vcr"], level: "info" } },
});

const logger = log4js.getLogger();
logger.info("some log event");

const events = recording.replay(); // events is an array of LogEvent objects.
recording.erase(); // clear the appender's array.