steno.js

let dict = qw`
  a from look say time about get make see to
  all give man she two also go many so up
  and have me some use as he more take very
  at her my tell want be here new than we
  because him no that well but his not the what
  by how now their when can I of them which
  come if on then who could in one there why
  day into onto these will do it or they with
  even its other thing would find just our think year
  first know out this you for like people those your
`
let chordOrder = []


// keyaddress is how chords are made,
// an address is the possible finger positions for
// a given finger.
// 1: frtg, 2: de, 3: sw, 4: aq
// 5: juyh, 6: juyh, 7: ki, 8: ;p
let finger_keys = qw`de fgtr sw aq1 ki jhnm lo ;p[`

let keyaddress = {}
let keys = []
let fingercount = 0
let fingerstate = [0,0,0,0, 0,0,0,0]
let freezestate = [0,0,0,0, 0,0,0,0]
let maxfingers = 0
let text = ''
let textcodes = ''
let hexchars = '0123456789ABCDEF'

main()
function main(){
  init()
  window.addEventListener('keydown', keydown)
  window.addEventListener('keyup', keyup)
}

function enumerateChordOrder(){
  chordOrder = []
  // goes over chords diagonally
  let diagscore = 2
  let diagindex = 0
  let j = 0;
  // max dictionary length
  // all hex numbers minus all single non-zero digit hex numbers minus the all zero number
  let n = 16**4 - 15*4 - 1
  n = Math.min(n, dict.length) 
  for(let i=0; i<n; ++i){
    if(++diagindex == diagscore){
      ++diagscore
      diagindex = 1
    }
    let a = diagindex
    let b = diagscore - a
    let f = Math.floor
    let hexstr = '' + hexchars[a%16]
    hexstr +=  hexchars[f(a/16)%16]
    hexstr += hexchars[b%16]
    hexstr += hexchars[f(b/16)%16]
    chordOrder.push(hexstr)
  }
  console.info('chord order', chordOrder.join(' '))
}

function init(){
  enumerateChordOrder()
  keyaddress = {}
  for(let i=0; i<finger_keys.length; ++i){
    let s = finger_keys[i]
    for(let j=0; j<s.length; ++j){
      keyaddress[s[j]] = [i, j+1]
    }
  }
}
function toHex(state){
  let result = ""
  let x = 0
  let n = 1
  for(let i=0; i<finger_keys.length; ++i){
    let m = finger_keys[i].length + 1
    if(n*m >= 16){
      result += hexchars[x]
      n = 1
      x = 0
    }
    x += (state[i]) * n
    n *= (m)
  }
  if(n > 1){
    result += hexchars[x]
  }
  return result   
}
function fingerstatus(){
  let s = fingerstate.join('')
  s = 'fingers: ' + s.substr(0,4) + ' ' + s.substr(4)
  let hex = '0123456789ABCDEF'
  s += `<br><br>hex code: ${toHex(fingerstate)}`
  //s += '<br><br>finger-hex: ' + hex[a] + hex[b] + ' ' + hex[d] + hex[c]
  id('status').innerHTML = s
}

function keydown(e){
  let {key} = e
  if(key in keyaddress){
    let [i, j] = keyaddress[key]
    if(fingerstate[i] == 0) ++fingercount
    fingerstate[i] = j
  }
  if(fingercount >= maxfingers){
    freezestate = fingerstate.slice(0)
    maxfingers = fingercount
  }
  fingerstatus()
}
function keyup(e){
  let {key} = e
  if(key in keyaddress){
    let [i, j] = keyaddress[key]
    fingerstate[i] = 0
    --fingercount
    if(fingercount == 0){
      if(maxfingers > 1)
        emit(freezestate)
      else
        input(key)
      maxfingers = 0
    }
  } else {
    input(key)
  }
  fingerstatus()
}
function writeTextCodes(x, y){
  while(x.length > y.length) y += ' '
  while(y.length > x.length) x += ' '
  text += x
  textcodes += y
  let out = id('textout')
  let codeout = id('codeout')
  out.innerHTML = ''
  out.appendChild(document.createTextNode(text))
  codeout.innerHTML = ''
  codeout.appendChild(document.createTextNode(textcodes))
}
function emit(state){
  let a = toHex(state)
  let i = chordOrder.indexOf(a)
  let b = i>=0? dict[i] : a
  writeTextCodes(' ' + b + ' ', ' ' + a + ' ')
}
function input(key){
  if(key.length == 1)
    writeTextCodes(key, key)
  else
    console.log(key)
  //console.log(key)
}

function qw(parts){
  return parts.join('').trim().split(/\s+/)
}
function id(x){
  return document.getElementById(x)
}