Edit in JSFiddle

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
	})
})