我是否可以配置console.log,以便将日志写入文件,而不是打印在控制台中?


当前回答

const fs = require("fs");
const {keys} = Object;
const {Console} = console;

/**
 * Redirect console to a file.  Call without path or with false-y
 * value to restore original behavior.
 * @param {string} [path]
 */
function file(path) {
    const con = path ? new Console(fs.createWriteStream(path)) : null;

    keys(Console.prototype).forEach(key => {
        if (path) {
            this[key] = (...args) => con[key](...args);
        } else {
            delete this[key];
        }
    });
};

// patch global console object and export
module.exports = console.file = file;

要使用它,可以这样做:

require("./console-file");
console.file("/path/to.log");
console.log("write to file!");
console.error("also write to file!");
console.file();    // go back to writing to stdout

其他回答

我采用了将输出流交换为我的流的想法。

const LogLater                = require ('./loglater.js');
var logfile=new LogLater( 'log'+( new Date().toISOString().replace(/[^a-zA-Z0-9]/g,'-') )+'.txt' );


var PassThrough = require('stream').PassThrough;

var myout= new PassThrough();
var wasout=console._stdout;
myout.on('data',(data)=>{logfile.dateline("\r\n"+data);wasout.write(data);});
console._stdout=myout;

var myerr= new PassThrough();
var waserr=console._stderr;
myerr.on('data',(data)=>{logfile.dateline("\r\n"+data);waserr.write(data);});
console._stderr=myerr;

loglater.js:

const fs = require('fs');

function LogLater(filename, noduplicates, interval) {
    this.filename = filename || "loglater.txt";
    this.arr = [];
    this.timeout = false;
    this.interval = interval || 1000;
    this.noduplicates = noduplicates || true;
    this.onsavetimeout_bind = this.onsavetimeout.bind(this);
    this.lasttext = "";
    process.on('exit',()=>{ if(this.timeout)clearTimeout(this.timeout);this.timeout=false; this.save(); })
}

LogLater.prototype = {
    _log: function _log(text) {
        this.arr.push(text);
        if (!this.timeout) this.timeout = setTimeout(this.onsavetimeout_bind, this.interval);
    },
    text: function log(text, loglastline) {
        if (this.noduplicates) {
            if (this.lasttext === text) return;
            this.lastline = text;
        }
        this._log(text);
    },
    line: function log(text, loglastline) {
        if (this.noduplicates) {
            if (this.lasttext === text) return;
            this.lastline = text;
        }
        this._log(text + '\r\n');
    },
    dateline: function dateline(text) {
        if (this.noduplicates) {
            if (this.lasttext === text) return;
            this.lastline = text;
        }
        this._log(((new Date()).toISOString()) + '\t' + text + '\r\n');
    },
    onsavetimeout: function onsavetimeout() {
        this.timeout = false;
        this.save();
    },
    save: function save() { fs.appendFile(this.filename, this.arr.splice(0, this.arr.length).join(''), function(err) { if (err) console.log(err.stack) }); }
}

module.exports = LogLater;

我经常使用很多参数console.log()和console.error(),所以我的解决方案是:

var fs = require('fs');
var util = require('util');
var logFile = fs.createWriteStream('log.txt', { flags: 'a' });
  // Or 'w' to truncate the file every time the process starts.
var logStdout = process.stdout;

console.log = function () {
  logFile.write(util.format.apply(null, arguments) + '\n');
  logStdout.write(util.format.apply(null, arguments) + '\n');
}
console.error = console.log;

如果您正在使用linux,您还可以使用输出重定向。Windows就不太确定了。

node server.js >> file.log 2>> file.log

>> file.log将标准输出重定向到文件

2>> file.log将stderr重定向到文件

其他人使用速记&>>作为stdout和stderr,但它不被我的MAC和ubuntu接受:(

额外:>覆盖,>>追加。

顺便说一下,关于NodeJS日志记录器,我使用pino + pino-pretty logger

const fs = require("fs");
const {keys} = Object;
const {Console} = console;

/**
 * Redirect console to a file.  Call without path or with false-y
 * value to restore original behavior.
 * @param {string} [path]
 */
function file(path) {
    const con = path ? new Console(fs.createWriteStream(path)) : null;

    keys(Console.prototype).forEach(key => {
        if (path) {
            this[key] = (...args) => con[key](...args);
        } else {
            delete this[key];
        }
    });
};

// patch global console object and export
module.exports = console.file = file;

要使用它,可以这样做:

require("./console-file");
console.file("/path/to.log");
console.log("write to file!");
console.error("also write to file!");
console.file();    // go back to writing to stdout

基于多参数版本的Clément,只是没有颜色代码的文本文件

var fs = require('fs');
var util = require('util');
var logFile = fs.createWriteStream('log.txt', { flags: 'a' });
  // Or 'w' to truncate the file every time the process starts.
var logStdout = process.stdout;

console.log = function () {
  // Storing without color codes
  logFile.write(util.format.apply(null,arguments).replace(/\033\[[0-9;]*m/g,"") + '\n');
  // Display normally, with colors to Stdout
  logStdout.write(util.format.apply(null, arguments) + '\n');
}

注:回答因为我不能评论