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The logger util that npm uses.

This logger is very basic. It does the logging for npm. It supportscustom levels and colored output.

By default, logs are written to stderr. If you want to send log messagesto outputs other than streams, then you can change thelog.streammember, or you can just listen to the events that it emits, and dowhatever you want with them.

npm install npmlog --save

varlog=require('npmlog')// additional stuff ---------------------------+// message ----------+                         |// prefix ----+      |                         |// level -+   |      |                         |//        v   v      v                         vlog.info('fyi','I have a kitty cat: %j',myKittyCat)

• {String}

The level to display logs at. Any logs at or above this level will bedisplayed. The special levelsilent will prevent anything from beingdisplayed ever.

• {Array}

An array of all the log messages that have been entered.

• {Number}

The maximum number of records to keep. If log.record gets bigger than10% over this value, then it is sliced down to 90% of this value.

The reason for the 10% window is so that it doesn't have to resize alarge array on every log entry.

• {Object}

A style object that specifies how prefixes are styled. (See below)

• {Object}

A style object that specifies how the heading is styled. (See below)

• {String} Default: ""

If set, a heading that is printed at the start of every line.

• {Stream} Default:process.stderr

The stream where output is written.

Force colors to be used on all messages, regardless of the outputstream.

Disable colors on all messages.

Enable the display of log activity spinner and progress bar

Disable the display of a progress bar

Force the unicode theme to be used for the progress bar.

Disable the use of unicode in the progress bar.

Set a template for outputting the progress bar. See thegauge documentation for details.

Select a themeset to pick themes from for the progress bar. See thegauge documentation for details.

Stop emitting messages to the stream, but do not drop them.

Emit all buffered messages that were written while paused.

• level {String} The level to emit the message at
• prefix {String} A string prefix. Set to "" to skip.
• message... Arguments toutil.format

Emit a log message at the specified level.

For example,

• log.silly(prefix, message, ...)
• log.verbose(prefix, message, ...)
• log.info(prefix, message, ...)
• log.http(prefix, message, ...)
• log.warn(prefix, message, ...)
• log.error(prefix, message, ...)

Likelog.log(level, prefix, message, ...). In this way, each level isgiven a shorthand, so you can dolog.info(prefix, message).

• level {String} Level indicator
• n {Number} The numeric level
• style {Object} Object with fg, bg, inverse, etc.
• disp {String} Optional replacement forlevel in the output.

Sets up a new level with a shorthand function and so forth.

Note that if the number isInfinity, then setting the level to thatwill cause all log messages to be suppressed. If the number is-Infinity, then the only way to show it is to enable all log messages.

• name {String} Optional; progress item name.
• todo {Number} Optional; total amount of work to be done. Default 0.
• weight {Number} Optional; the weight of this item relative to others. Default 1.

This adds a neware-we-there-yet item tracker to the progress tracker. Theobject returned has thelog[level] methods but is otherwise anare-we-there-yetTracker object.

This adds a neware-we-there-yet stream tracker to the progress tracker. Theobject returned has thelog[level] methods but is otherwise anare-we-there-yetTrackerStream object.

This adds a neware-we-there-yet tracker group to the progress tracker. Theobject returned has thelog[level] methods but is otherwise anare-we-there-yetTrackerGroup object.

Events are all emitted with the message object.

• log Emitted for all messages
• log.<level> Emitted for all messages with the<level> level.
• <prefix> Messages with prefixes also emit their prefix as an event.

Style objects can have the following fields:

• fg {String} Color for the foreground text
• bg {String} Color for the background
• bold,inverse,underline {Boolean} Set the associated property
• bell {Boolean} Make a noise (This is pretty annoying, probably.)

Every log event is emitted with a message object, and thelog.recordlist contains all of them that have been created. They have thefollowing fields:

• id {Number}
• level {String}
• prefix {String}
• message {String} Result ofutil.format()
• messageRaw {Array} Arguments toutil.format()

We useset-blocking to setstderr and stdout blocking if they are tty's and have the setBlocking call.This is a work around for an issue in early versions of Node.js 6.x, whichmade stderr and stdout non-blocking on OSX. (They are always blockingWindows and were never blocking on Linux.)npmlog needs them to be blockingso that it can allow output to stdout and stderr to be interlaced.