90 lines
3.0 KiB
Markdown
90 lines
3.0 KiB
Markdown
|
# proc-log
|
|||
|
|
|
|||
|
|
Emits 'log' events on the process object which a log output listener can
|
|||
|
|
consume and print to the terminal.
|
|||
|
|
|
|||
|
|
This is used by various modules within the npm CLI stack in order to send
|
|||
|
|
log events that can be consumed by a listener on the process object.
|
|||
|
|
|
|||
|
|
## API
|
|||
|
|
|
|||
|
|
* `log.error(...args)` calls `process.emit('log', 'error', ...args)`
|
|||
|
|
The highest log level. For printing extremely serious errors that
|
|||
|
|
indicate something went wrong.
|
|||
|
|
* `log.warn(...args)` calls `process.emit('log', 'warn', ...args)`
|
|||
|
|
A fairly high log level. Things that the user needs to be aware of, but
|
|||
|
|
which won't necessarily cause improper functioning of the system.
|
|||
|
|
* `log.notice(...args)` calls `process.emit('log', 'notice', ...args)`
|
|||
|
|
Notices which are important, but not necessarily dangerous or a cause for
|
|||
|
|
excess concern.
|
|||
|
|
* `log.info(...args)` calls `process.emit('log', 'info', ...args)`
|
|||
|
|
Informative messages that may benefit the user, but aren't particularly
|
|||
|
|
important.
|
|||
|
|
* `log.verbose(...args)` calls `process.emit('log', 'verbose', ...args)`
|
|||
|
|
Noisy output that is more detail that most users will care about.
|
|||
|
|
* `log.silly(...args)` calls `process.emit('log', 'silly', ...args)`
|
|||
|
|
Extremely noisy excessive logging messages that are typically only useful
|
|||
|
|
for debugging.
|
|||
|
|
* `log.http(...args)` calls `process.emit('log', 'http', ...args)`
|
|||
|
|
Information about HTTP requests made and/or completed.
|
|||
|
|
* `log.pause()` calls `process.emit('log', 'pause')` Used to tell
|
|||
|
|
the consumer to stop printing messages.
|
|||
|
|
* `log.resume()` calls `process.emit('log', 'resume')`
|
|||
|
|
Used to tell the consumer that it is ok to print messages again.
|
|||
|
|
* `log.LEVELS` an array of strings of all log method names
|
|||
|
|
|
|||
|
|
## Examples
|
|||
|
|
|
|||
|
|
Every method calls `process.emit('log', level, ...otherArgs)` internally.
|
|||
|
|
So in order to consume those events you need to do `process.on('log', fn)`.
|
|||
|
|
|
|||
|
|
### Colorize based on level
|
|||
|
|
|
|||
|
|
Here's an example of how to consume `proc-log` events and colorize them
|
|||
|
|
based on level:
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
const chalk = require('chalk')
|
|||
|
|
|
|||
|
|
process.on('log', (level, ...args) => {
|
|||
|
|
if (level === 'error') {
|
|||
|
|
console.log(chalk.red(level), ...args)
|
|||
|
|
} else {
|
|||
|
|
console.log(chalk.blue(level), ...args)
|
|||
|
|
}
|
|||
|
|
})
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
### Pause and resume
|
|||
|
|
|
|||
|
|
`pause` and `resume` are included so you have the ability to tell your consumer
|
|||
|
|
that you want to pause or resume your display of logs. In the npm CLI we use
|
|||
|
|
this to buffer all logs on init until we know the correct loglevel to display.
|
|||
|
|
But we also setup a second handler that writes everything to a file even if
|
|||
|
|
paused.
|
|||
|
|
|
|||
|
|
```js
|
|||
|
|
let paused = true
|
|||
|
|
const buffer = []
|
|||
|
|
|
|||
|
|
// this handler will buffer and replay logs only
|
|||
|
|
// after `procLog.resume()` is called
|
|||
|
|
process.on('log', (level, ...args) => {
|
|||
|
|
if (level === 'resume') {
|
|||
|
|
buffer.forEach((item) => console.log(...item))
|
|||
|
|
paused = false
|
|||
|
|
return
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
if (paused) {
|
|||
|
|
buffer.push([level, ...args])
|
|||
|
|
} else {
|
|||
|
|
console.log(level, ...args)
|
|||
|
|
}
|
|||
|
|
})
|
|||
|
|
|
|||
|
|
// this handler will write everything to a file
|
|||
|
|
process.on('log', (...args) => {
|
|||
|
|
fs.appendFileSync('debug.log', args.join(' '))
|
|||
|
|
})
|
|||
|
|
```
|