Uses old Rust 2015
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#31 in #es
220KB
5.5K
SLoC
Pax
The fastest JavaScript bundler in the galaxy. Fully supports ECMAScript module syntax (import
/export
) in addition to CommonJS require(<string>)
.
- Why do I need it?
- How do I get it?
- How do I use it?
- Does it do source maps?
- Modules?
- What are the options?
- Is it fast?
Why do I need it?
Because your bundler is too slow.
You know the feeling. You make that tweak, hit ⌘S ⌘Tab ⌘R, and… nothing changes. You get the old version. You beat the bundler. You wait a few seconds, hit ⌘R again, and your changes finally show up. But it’s too late—you’ve lost momentum. It’s the wrong shade of pink. You spelled “menu” with a z. The bug still happens sometimes.
Rinse. Repeat. Ten cycles later, things are looking good. It’s time to git commit
. But you spent more time waiting than working. And it’s your bundler’s fault.
Pax is a bundler. But you’ll never beat it. Why?
- It’s parallelized. It makes the most of your cores.
- It’s minimal. It isn’t bogged down by features you don’t need.
- It knows exactly enough about JavaScript to handle dependency resolution. It doesn’t even bother parsing most of your source code.
Don’t waste time waiting for your bundler to do its thing. Use Pax while you’re developing, and iterate to your heart’s content. Use your super-cool, magical, slow-as-molasses bundler for releases, when you don’t care how long it takes to run.
How do I get it?
> cargo install pax
If you don’t have cargo
, install it with https://rustup.rs.
How do I use it?
// index.js:
const itt = require('itt')
const math = require('./math')
console.log(itt.range(10).map(math.square).join(' '))
// math.js:
exports.square = x => x * x
> px index.js bundle.js
Slap on a <script src=bundle.js>
, and you’re ready to go. Pass -w
to rebuild whenever you change a file.
> px -w index.js bundle.js
ready bundle.js in 1 ms
update bundle.js in 1 ms
...
Does it do source maps?
Of course!
# bundle.js and bundle.js.map
> px index.js bundle.js
# bundle.js with inline map
> px --map-inline index.js bundle.js
# bundle.js with no source map
> px index.js >bundle.js
# or
> px --no-map index.js bundle.js
Modules?
That’s technically not a question. But yes.
// index.mjs
import itt from 'itt'
import { square, cube } from './math'
console.log(itt.range(10).map(square).join(' '))
console.log(itt.range(10).map(cube).join(' '))
// math.mjs
export const square = x => x * x, cube = x => x * x * x
> px -e index.mjs bundle.js
If you need your modules to be in .js
files for some reason, use -E
(--es-syntax-everywhere
) instead of -e
(--es-syntax
).
What are the options?
> px --help
pax v0.4.0
Usage:
px [options] <input> [output]
px [-h | --help]
Options:
-i, --input <input>
Use <input> as the main module.
-o, --output <output>
Write bundle to <output> and source map to <output>.map.
Default: '-' for stdout.
-m, --map <map>
Output source map to <map>.
-I, --map-inline
Output source map inline as data: URI.
-M, --no-map
Suppress source map output when it would normally be implied.
-w, --watch
Watch for changes to <input> and its dependencies.
-W, --quiet-watch
Don't emit a bell character for errors that occur while watching.
Implies --watch.
-e, --es-syntax
Support .mjs files with ECMAScript module syntax:
import itt from 'itt'
export const greeting = 'Hello, world!'
Instead of CommonJS require syntax:
const itt = require('itt')
exports.greeting = 'Hello, world!'
.mjs (ESM) files can import .js (CJS) files, in which case the
namespace object has a single `default` binding which reflects the
value of `module.exports`. CJS files can require ESM files, in which
case the resultant object is the namespace object.
-E, --es-syntax-everywhere
Implies --es-syntax. Allow ECMAScript module syntax in .js files.
CJS-style `require()` calls are also allowed.
-x, --external <module1,module2,...>
Don't resolve or include modules named <module1>, <module2>, etc.;
leave them as require('<module>') references in the bundle. Specifying
a path instead of a module name does nothing.
--external-core
Ignore references to node.js core modules like 'events' and leave them
as require('<module>') references in the bundle.
-h, --help
Print this message.
-v, --version
Print version information.
Is it fast?
Umm…
Yes.
> time browserify index.js >browserify.js
real 0m0.225s
user 0m0.197s
sys 0m0.031s
> time node fuse-box.js
real 0m0.373s
user 0m0.324s
sys 0m0.051s
> time px index.js >bundle.js
real 0m0.010s
user 0m0.005s
sys 0m0.006s
# on a larger project
> time browserify src/main.js >browserify.js
real 0m2.385s
user 0m2.459s
sys 0m0.416s
> time px src/main.js >bundle.js
real 0m0.037s
user 0m0.071s
sys 0m0.019s
# want source maps?
> time browserify -d src/main.js -o bundle.js
real 0m3.142s
user 0m3.060s
sys 0m0.483s
> time px src/main.js bundle.js
real 0m0.046s
user 0m0.077s
sys 0m0.026s
# realtime!
> px -w examples/simple bundle.js
ready bundle.js in 2 ms
update bundle.js in 2 ms
update bundle.js in 2 ms
update bundle.js in 1 ms
update bundle.js in 2 ms
update bundle.js in 1 ms
update bundle.js in 3 ms
^C
Dependencies
~4–12MB
~147K SLoC