watch mode for browserify builds


watch mode for browserify builds

Update any source file and your browserify bundle will be recompiled on the spot.


$ watchify main.js -o static/bundle.js

Now as you update files, static/bundle.js will be automatically incrementally rebuilt on the fly.

The -o option can be a file or a shell command (not available on Windows) that receives piped input:

watchify main.js -o 'exorcist static/ > static/bundle.js' -d
watchify main.js -o 'uglifyjs -cm > static/bundle.min.js'

You can use -v to get more verbose output to show when a file was written and how long the bundling took (in seconds):

$ watchify browser.js -d -o static/bundle.js -v
610598 bytes written to static/bundle.js (0.23 seconds)
610606 bytes written to static/bundle.js (0.10 seconds)
610597 bytes written to static/bundle.js (0.14 seconds)
610606 bytes written to static/bundle.js (0.08 seconds)
610597 bytes written to static/bundle.js (0.08 seconds)
610597 bytes written to static/bundle.js (0.19 seconds)


Use watchify with all the same options as browserify except that -o (or --outfile) is mandatory. Additionally, there are also:

Standard Options:
  --outfile=FILE, -o FILE
    This option is required. Write the browserify bundle to this file. If
    the file contains the operators `|` or `>`, it will be treated as a
    shell command, and the output will be piped to it (not available on
  --verbose, -v                     [default: false]
    Show when a file was written and how long the bundling took (in
    Show the watchify and browserify versions with their module paths.
Advanced Options:
  --delay                           [default: 600]
    Amount of time in milliseconds to wait before emitting an "update"
    event after a change.
  --ignore-watch=GLOB, --iw GLOB    [default: false]
    Ignore monitoring files for changes that match the pattern. Omitting
    the pattern will default to "**/node_modules/**".
  --poll=INTERVAL                   [default: false]
    Use polling to monitor for changes. Omitting the interval will default
    to 100ms. This option is useful if you're watching an NFS volume.


var watchify = require('watchify');
var fromArgs = require('watchify/bin/args');

Wrap a browserify bundle b with watchify, returning the wrapped bundle instance as w.

When creating the browserify instance b you MUST set these properties in the constructor:

var b = browserify({ cache: {}, packageCache: {} });
var w = watchify(b);

You can also just do:

var b = browserify(watchify.args);
var w = watchify(b);

By default, watchify doesn't display any output, see events for more info.

w is exactly like a browserify bundle except that caches file contents and emits an 'update' event when a file changes. You should call w.bundle() after the 'update' event fires to generate a new bundle. Calling w.bundle() extra times past the first time will be much faster due to caching.

Important: Watchify will not emit 'update' events until you've called w.bundle() once and completely drained the stream it returns. This can be achieved by writing the result to a file. If you aren't writing to a file before the 'update' event fires, you will need:

var b = browserify(watchify.args);
var w = watchify(b);
// Without the line, update events won't be fired 
w.bundle().on('data', function() {});

Once the 'end' event fires on the stream returned by this w.bundle(), 'update' events will start to arrive as changes occur on the filesystem.

opts.delay is the amount of time in milliseconds to wait before emitting an "update" event after a change. Defaults to 600.

opts.ignoreWatch ignores monitoring files for changes. If set to true, then **/node_modules/** will be ignored. For other possible values see Chokidar's documentation on "ignored".

opts.poll enables polling to monitor for changes. If set to true, then a polling interval of 100ms is used. If set to a number, then that amount of milliseconds will be the polling interval. For more info see Chokidar's documentation on "usePolling" and "interval". This option is useful if you're watching an NFS volume.

Close all the open watch handles.

Create a watchify instance w from an array of arguments args. The required constructor parameters will be set up automatically.


When the bundle changes, emit the array of bundle ids that changed.

When a bundle is generated, this event fires with the number of bytes.

When a bundle is generated, this event fires with the time it took to create the bundle in milliseconds.

This event fires after a bundle was created with messages of the form:

X bytes written (Y seconds)

with the number of bytes in the bundle X and the time in seconds Y.


With npm do:

$ npm install -g watchify

to get the watchify command and:

$ npm install watchify

to get just the library.


It may be related to a bug in fsevents (see #250 and SO). Try the --poll flag and/or renaming the project's directory - that might help.