如何获取Nodejs中显示的console.log行号？

Got an old application, that prints out quite a lot of messages using console.log, but I just can not find in which files and lines console.log is called.

有一个旧的应用程序,使用console.log打印出相当多的消息,但我无法找到调用console.log的文件和行。

Is there a way to hook into the app and show file name and line numbers?

有没有办法挂钩应用程序并显示文件名和行号?

3 个解决方案

#1

For a temporary hack to find the log statements that you want to get rid of, it's not too difficult to override console.log yourself.

对于临时hack来找到你想要删除的日志语句,自己覆盖console.log并不困难。

var log = console.log;
console.log = function() {
    log.apply(console, arguments);
    // Print the stack trace
    console.trace();
};


// Somewhere else...
function foo(){
    console.log('Foobar');
}
foo();

That will print something like

这将打印出类似的东西

Foobar
Trace
at Console.console.log (index.js:4:13)
at foo (index.js:10:13)
at Object.<anonymous> (index.js:12:1)
...

A lot of noise in there but the second line in the call stack, at foo (index.js:10:13), should point you to the right place.

那里有很多噪音,但是调用堆栈中的第二行,在foo(index.js:10:13),应该指向正确的位置。

#2

Having full stack trace for each call is a bit noisy. I've just improved the @noppa's solution to print only the initiator:

每个呼叫都有完整的堆栈跟踪有点吵。我刚刚改进了@noppa的解决方案,只打印启动器:

['log', 'warn', 'error'].forEach((methodName) => {
  const originalMethod = console[methodName];
  console[methodName] = (...args) => {
    let initiator = 'unknown place';
    try {
      throw new Error();
    } catch (e) {
      if (typeof e.stack === 'string') {
        let isFirst = true;
        for (const line of e.stack.split('\n')) {
          const matches = line.match(/^\s+at\s+(.*)/);
          if (matches) {
            if (!isFirst) { // first line - current function
                            // second line - caller (what we are looking for)
              initiator = matches[1];
              break;
            }
            isFirst = false;
          }
        }
      }
    }
    originalMethod.apply(console, [...args, '\n', `  at ${initiator}`]);
  };
});

It also patches other methods (useful for Nodejs, since warn and error don't come with a stack trace as in Chrome).

它还修补了其他方法(对Nodejs很有用,因为警告和错误不会像Chrome一样带有堆栈跟踪)。

So your console would look something like:

所以你的控制台看起来像:

Loading settings.json
   at fs.readdirSync.filter.forEach (.../settings.js:21:13)
Server is running on http://localhost:3000 or http://127.0.0.1:3000
   at Server.app.listen (.../index.js:67:11)

#3

I found Dmitry Druganov's answer really nice, but I tried it on Windows 10 (with Node 8.9.4) and it didn't work well. It was printing the full path, something like:

我发现德米特里·德鲁加诺夫的答案非常好,但我在Windows 10(使用Node 8.9.4)上尝试过它并且效果不佳。它打印了完整的路径,如:

Loading settings.json
   at fs.readdirSync.filter.forEach (D:\Users\Piyin\Projects\test\settings.js:21:13)
Server is running on http://localhost:3000 or http://127.0.0.1:3000
   at Server.app.listen (D:\Users\Piyin\Projects\test\index.js:67:11)

So I took said answer and made these improvements (from my point of view):

所以我接受了所说的答案并做了这些改进(从我的角度来看):

Assume the important line of the stack trace is the third one (the first one is the word Error and the second one is where you place this script)

假设堆栈跟踪的重要行是第三行(第一行是单词Error,第二行是放置此脚本的位置)

Remove the current script folder path (given by __dirname, which in my case is D:\Users\Piyin\Projects\test). Note: For this to work well, the script should be on the project's main Javascript

删除当前脚本文件夹路径(由__dirname给出,在我的例子中是D:\ Users \ Piyin \ Projects \ test)。注意:为了使其正常工作,脚本应该在项目的主要Javascript上

Remove the starting at

删除起点

Place the file information before the actual log

将文件信息放在实际日志之前

Format the information as Class.method at path/to/file:line:column

将信息格式化为Class.method在path / to / file:line:column

Here it is:

这里是:

['log','warn','error'].forEach((methodName) => {
  const originalMethod = console[methodName];
  console[methodName] = (...args) => {
    try {
      throw new Error();
    } catch (error) {
      originalMethod.apply(
        console,
        [
            error
            .stack // Grabs the stack trace
            .split('\n')[2] // Grabs third line
            .trim() // Removes spaces
            .substring(3) // Removes three first characters ("at ")
            .replace(__dirname, '') // Removes script folder path
            .replace(/\s\(./, ' at ') // Removes first parentheses and replaces it with " at "
            .replace(/\)/, '') // Removes last parentheses
          ),
          '\n',
          ...args
        ]
      );
    }
  };
});

And here's the new output:

这是新的输出:

fs.readdirSync.filter.forEach at settings.js:21:13
 Loading settings.json
Server.app.listen at index.js:67:11
 Server is running on http://localhost:3000 or http://127.0.0.1:3000

Here's the minified-by-hand code (240 bytes):

这是手工编写的代码(240字节):

['log','warn','error'].forEach(a=>{let b=console[a];console[a]=(...c)=>{try{throw new Error}catch(d){b.apply(console,[d.stack.split('\n')[2].trim().substring(3).replace(__dirname,'').replace(/\s\(./,' at ').replace(/\)/,''),'\n',...c])}}});

#1