Escape Unicode Characters

function escapeUnicode(s) {
    return s.replace(/[^\x20-\x7e]/g, function (c) {
        c = c.charCodeAt(0);
        if (c == 8) c = '\\b';
        else if (c == 9) c = '\\t';
        else if (c == 10) c = '\\n';
        else if (c == 12) c = '\\f';
        else if (c == 13) c = '\\r';
        else if (c < 128) c = '\\x' + (c < 16 ? '0' : '') + c.toString(16);
        else c = c.toString(16), c = '\\u' + ('000' + c).slice(-4);
        return c;
    });
}

console.log(escapeUnicode('吉 – удача.')); // "\u5409 \u2013 \u0443\u0434\u0430\u0447\u0430."