stringify is the helper function which does the actual work of producing a Ratlog compliant string.
Normally it doesn't need to be used directly, but it is exposed just in case.
RatlogData represents an unprocessed log as data.
Ratlogger is the main logging function.
Ratlogger takes a message, an object of fields and a rest of tags.
No argument is required, but the typings force you to at least provide a message. That is a good practise because an empty log line is mostly meaningless.
fields and tags are optional:
log('hey there')If you want to add tags but no fields, you can omit the fields:
log('msg', 'mytag').tag() returns a new logger bound to one or more tags.
The returned Ratlogger workes identical to above with the only difference that some tags are always set.
const warn = log.tag('warn')
warn('it is late')
// => [warn] it is lateRatlog tries its best to get a string representation of values passed to it.
If possible values should be passed as strings directly.
Otherwise Ratlog tries calling .toString() on the given value.
Errors are catched in case that fails. Logging should never fail. But it is not pretty.
null and undefined are converted to empty strings.
ToString is automatically implemented by any object with a .toString() method.
Most JavaScript values already implement it by default, but if you have complex data types, you can create your own implementation to create a more readable representation.
Writer is a narrow interface for the stream or function passed to the Ratlog constructor.
In practise you would mostly want to pass a stream like process.stdout
but having this narrow interface allows you to
easily create mock versions for testing and so on.
By implementing your own writer, you could even use Ratlog in the browser:
const log = ratlog(console.log)The default export is a function to create a logger.
See Ratlog at the top of this document.
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The default export is a function that creates a logger.
All it does is returning a log function bound to a writable stream or function.
Example:
const ratlog = require('ratlog') const log = ratlog(process.stdout)The logger can also be directly created with one or more tags:
const critical = ratlog(process.stderr, 'warn', 'critical') critical('oh no!') // => [warn|critical] oh no!Alternatively a customized logger can be created using
ratlog.logger()andratlog.stringify().This can be used to filter out logs with certain tags:
const log = ratlog.logger(log => { if (process.env.DEBUG || !log.tags.includes('debug')) { process.stdout.write(ratlog.stringify(log)) } })Or one can only use the Ratlog logging API but skip the output format and use JSON instead:
const log = ratlog.logger(log => { process.stdout.write(JSON.stringify(log)) })