全角かな or カナを半角カナに変換する【JS】

<div>
    <div>
        <div>
            <div>
                <label>input</label>
                <textarea id="src"></textarea>
                <label>output</label>
                <textarea id="dst"></textarea>
                <div>
                    <button id="run">run</button>
                </div>
                <select id="kana-type">
                    <option value="all" selected>全て変換</option>
                    <option value="hiragana">かなのみ変換</option>
                    <option value="katakana">カナのみ変換</option>
                </select>
            </div>
        </div>
    </div>
</div>

const KANA = {
  "normal": {
    "src": {
      "hiragana":"あいうえおかきくけこさしすせそたちつてとなにぬねのはひふへほまみむめもやゆよらりるれろわをんぁぃぅぇぉヵヶっゃゅょゎ。、「」ー",
      "katakana":"アイウエオカキクケコサシスセソタチツテトナニヌネノハヒフヘホマミムメモヤユヨラリルレロワヲンァィゥェォヵヶッャュョヮ。、「」ー",
    },
    "dst": "ｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃﾄﾅﾆﾇﾈﾉﾊﾋﾌﾍﾎﾏﾐﾑﾒﾓﾔﾕﾖﾗﾘﾙﾚﾛﾜｦﾝｧｨｩｪｫヵヶｯｬｭｮﾜ｡､｢｣-",
    "suffix" : ""
  },
  "dakuon": {
    "src" : {
            "hiragana": "がぎぐげござじずぜぞだぢづでどばびぶべぼゔ",
      "katakana": "ガギグゲゴザジズゼゾダヂヅデドバビブベボヴ",
    },
    "dst":"ｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃﾄﾊﾋﾌﾍﾎｳ",
    "suffix" : "ﾞ"
  },
  "handakuon": {
    "src": {
      "hiragana": "ぱぴぷぺぽ",
      "katakana": "パピプペポ",
    },
    "dst" : "ﾊﾋﾌﾍﾎ",
    "suffix" : "ﾟ"
  }
};

document.getElementById("run").addEventListener("click", (e) => {
  var input = document.getElementById("src")
  var output = document.getElementById("dst")
  var type = document.getElementById("kana-type")
  
  output.value = ""
  
  var zenkaku = []
  var hankaku = []

  for (var key1 in KANA) {
    var src = KANA[key1].src
    var dst = KANA[key1].dst
    var suffix = ""

    if (KANA[key1].suffix) {
      suffix = KANA[key1].suffix
    }

    for (var key2 in src) {
      if (type.value === "all" || key2 === type.value) {
        var row = src[key2]
        for (var j = 0; j < row.length; j++) {
          zenkaku.push(row[j] + suffix)
          hankaku.push(dst[j] + suffix)
        }
      }
    }
  }

  input.value.split("").forEach((e) => {
    for (var i = 0; i < zenkaku.length; i++) {
      if (zenkaku[i] == e) {
        output.value += hankaku[i]
        return
      }
    }
    output.value += e
  })
})