bumpy.js

var code = document.getElementById('code'); code.addEventListener('keyup', e => {
    const v = code.value
    const d = document.getElementById('debug')
    if (v.length >= 2) {
      for (var i = 0; i < v.length - 2; i++) {
        if (! ((v[i]<v[i+1]&&v[i+1]>v[i+2]) || (v[i]>v[i+1]&&v[i+1]<v[i+2]))) {
          d.value = 'Not bumpy! ' + v[i] + v[i+1] + v[i+2]
          return
        }
      }
      const ascii = new Array(95).fill(0).map((x,i)=>String.fromCharCode(i+32))
      if (v[v.length-2] < v[v.length-1]) {
        d.value = 'Next: ' + ascii.filter(c => v[v.length-1] > c).join``
      } else {
        d.value = 'Next: ' + ascii.filter(c => v[v.length-1] < c).join``
      }
    } else { d.value = '' }
})