lib/jaconv.js
function toHiragana(s) {
        var res = '';
        for (var i = 0; i < s.length; i += 1) {
            var cd = s.charCodeAt(i);
            res += (minKata <= cd && cd <= maxKata) ?
                String.fromCharCode(cd - minKata + minHira) : s.charAt(i);
        }
        return res;
    }
function toHiragana(s) {
        var res = '';
        for (var i = 0; i < s.length; i += 1) {
            var cd = s.charCodeAt(i);
            res += (minKata <= cd && cd <= maxKata) ?
                String.fromCharCode(cd - minKata + minHira) : s.charAt(i);
        }
        return res;
    }
全角カタカナを全角ひらがなに変換します。