/**
 * 最大公約数を求める
 */
function gcd(x, y){
  if(y === 0) return x
  return gcd(y, x % y)
 }


/**
 * 予め決めておいたアスペクト比の計算
 */
const arr = ['res1','res2','res3']
for(let i = 0, iLen = arr.length; i < iLen; i++){
  const id = arr[i]
  const res = document.getElementById(id)
  const w = res.dataset.w
  const h = res.dataset.h
  const g = gcd(w,h)
  const ratio_w = w / g
  const ratio_h = h / g
  
  res.innerHTML = `結果：${ratio_w}:${ratio_h}`
}


const btn = document.getElementById('res-btn')
const ops_res = document.getElementById('res4')
const ops_w = document.getElementById('ratio-w')
const ops_h = document.getElementById('ratio-h')


/**
 * 任意に入力したサイズのアスペクト比を計算
 */
btn.addEventListener('click', ()=>{
  const w = ops_w.value - 0
  const h = ops_h.value - 0
  const g = gcd(w,h)
  const x = w / g
  const y = h / g
  
  ops_res.innerHTML = `結果：${x}:${y}`
}, false)