keysquash

An experimental JS "compression" pass that stores an index of long, frequently used key names

keysquash

Keysquash is an experimental JS "compression" pass that stores an index of long, frequently used key names (e.g. addEventListener) and refers to that instead.

For example:

document.body.addEventListener('mousedown', function(e) {
  console.log('down', e.offsetX, e.offsetY)
})
document.body.addEventListener('mouseup', function(e) {
  console.log('up', e.offsetX, e.offsetY)
})

Would be transformed into this:

(function($__ks_) {
  document.body[$__ks_._]('mousedown', function(e) {
    console.log('down', e[$__ks_.$], e[$__ks_.a])
  })
  document.body[$__ks_._]('mousedown', function(e) {
    console.log('down', e[$__ks_.$], e[$__ks_.a])
  })
})({
    "_": "addEventListener"
  , "$": "offsetX"
  , "a": "offsetY"
})

Which can then get minified using uglifyjs -cm for further savings.

In practice it's a little smarter about making sure that replacing keys provides a file size improvement too, but make sure to double check this.

This is only worth using in special cases such as js13kgames. I'm not sure of all of the side-effects yet.

npm install -g keysquash
cat index.js | keysquash | uglifyjs -cm