一个简单的日志module, 功能如下

时间显示

调用log的文件名与行号显示

不同日志级别使用不同颜色输出

支持stdout输出的同时写入文件日志

文件日志使用缓存以降低io次数

使用示例

var log = require('./log'),

	logWithoutFile = log.create();

	logWithFile = log.create(log.WARNING, 'my.log'),



logWithoutFile.info('info msg');

logWithoutFile.debug('debug msg');

logWithoutFile.warning('warning msg');

logWithoutFile.error('error msg');

logWithoutFile.trace('trace msg');



logWithFile.info('info msg');

logWithFile.debug('debug msg');

logWithFile.warning('warning msg');

logWithFile.error('error msg');

logWithFile.trace('trace msg');

输出效果

源码如下

var fs = require('fs');



var cwd = process.cwd() + '/',

	INFO = 0;

	DEBUG = 1;

	WARNING = 2;

	ERROR = 3;

	TRACE = 4;

	INIT = 6;

	type = ['INFO', 'DEBUG', 'WARNING', 'ERROR', 'TRACE', '', 'LOG_INIT'];

	colors = [38, 34, 35, 31, 32, 36, 33];

	bufferSize = 20000;

	writeSize = 16384;



exports.INFO = INFO;

exports.DEBUG = DEBUG;

exports.WARNING = WARNING;

exports.ERROR = ERROR;

exports.TRACE = TRACE;



function getPos() {

	try {

		throw new Error();

	} catch(e) {

		var pos = e.stack.split('\n')[4].split('(')[1].split(')')[0].split(':');

		return pos[0].replace(cwd, '') + ':' + pos[1];

	}

}



function pad2(num) {

	return num > 9 ? num : '0' + num;

}



function getTime() {

	var t = new Date();

	return [t.getFullYear(), '-', pad2(t.getMonth() + 1) , '-', pad2(t.getDate()), ' ',

		pad2(t.getHours()), ':', pad2(t.getMinutes()), ':', pad2(t.getSeconds())].join('');

}



function formatLog(log, color) {

	var tag = head = foot = '';

	if (color) {

		head = '\x1B[';

		foot = '\x1B[0m';

		tag = colors[5]+'m';

		color = colors[log.type]+'m';

	}



return [log.time, ' [', head, color, type[log.type], foot, '] [', head, tag, log.pos, foot, '] ', log.msg].join('');

}



exports.create = function(level, file) {

	if (!level) {

		level = INFO;

	}

	if (file) {

		var buffer = new Buffer(bufferSize);

		var pos = 0;

		var fd = fs.openSync(file, 'a');

		process.on('exit', function(){

			fs.writeSync(fd, buffer, 0, pos, null);

		})

	}

	function log(type, msg) {

		if (type < level){

			return;

		}

		var log = {type:type, msg:msg, time:getTime(), pos:getPos()};

		console.log(formatLog(log, true));

		if (file) {

			if (pos >= writeSize) {

				fs.writeSync(fd, buffer, 0, pos, null);

				pos = 0;

			}

			pos += buffer.write(formatLog(log) + "\r\n", pos);

		}

	}

	console.log(formatLog({type:INIT, pos:file, time:getTime(), msg: 'log init with level ' + type[level]}, true));

	return {

		info : function(msg) {log(INFO, msg);},

		debug : function(msg) {log(DEBUG, msg);},

		warning : function(msg) {log(WARNING, msg);},

		error : function(msg) {log(ERROR, msg);},

		trace : function(msg) {log(TRACE, msg);},

	};

}