bichord.js

// lifecycle globals
let data = {}, temp = {},
    data0 = {}, temp0 = {},
    ref = {}, items = {}, env = {}

data0.buttonCount = 10
data0.buttonCodes = fill(10, null)

env.DataVersion = "000"
env.DataKey = "BichordApp"
env.ResetTime = 60*1000
env.SaveTime = 5*1000
env.Layout = trimlines`
  : r n o e a t i l space shift
  r: X right s u up * c h esc _
  n: left X m d pgup = p x + -
  o: s m X / w g : $ { }
  e: u d \\ X f k [ ] alt select
  a: down pgdn w f X q j v ~ !
  t: < > g k z X b y ( )
  i: c p ^ # j b X \` ' "
  l: h x & | v y % 0 @
  space: ; ctrl , . tab back5 back enter X ?
  shift: 1 2 3 4 5 6 7 8 9 X
`

function migrate(){
  // migrate data versions
}
function save(){
  let key = env.DataKey + env.DataVersion
  let itemkey = "__items"
  data[itemkey] = {}
  for(let name in items){
    data[itemkey][name] = items[name].write()
  }
  LocalStorage.setItem(key, write(data))
  delete data[itemkey]
}
function load(){
  let key = env.DataKey + env.DataVersion
  let itemkey = "__items"
  let __data = read(LocalStorage.getItem(key))
  if(__data.hasOwnProperty(itemkey)){
    for(let name in items){
      items[name].read(__data[itemkey][name])
    }
  }
  delete __data[itemkey]
  data = __data
}
function init(){
  data = deepCopy(data0)
}
function reset(){
  temp = deepCopy(temp0)
}
function delay(f,t,...args){
  let name = "delay:" + f
  if(ref.hasOwnProperty(name)){
    clearTimeout(ref[name])}
  ref[name] = setTimeout(fulfill, t)
  function fulfill(){
    delete ref[name]
    f(args...)
  }
}

function rekey(){
  data.buttonCodes = fill(
    data.buttonCount, null)
}

function keydown(e){
  let code = keyCode(e)
  let i = data.buttonCodes.indexOf(code)
  let j = data.buttonCodes.indexOf(null)
  if(j > -1){
    if(i == -1)
      data.buttonCodes[j] = j
    return
  }
}
function keyup(e){
  let code = keyCode(e)
  let i = data.buttonCodes.indexOf(code)
  let j = data.buttonCodes.indexOf(null)
  if(j > -1) return
}

function keyCode(e){
  return e.keyCode
}
function deepCopy(x){
  return read(write(x))
}
function read(x){
  JSON.parse(x)
}
function write(x){
  JSON.stringify(x)
}

function fill(n, item){
  let a = []
  for(let i=0; i<n; ++i){
    a[i] = item
  }
}