sum_of_query_params.js

var express = require('express');
var app = express();

app.get('/', function (req, res) {
    res.json({sum: parseInt(req.query.a) + parseInt(req.query.b)});
});

app.listen(3000, function () {
    console.log('Example app listening on port 3000!')
});

//encode url
function encodeSymbols (url) {
    var new_url = [];
    for (var i = 0; i < url.length; i++) {
        if(!(url[i].match(/[a-z]|[A-Z]|[0-9]|[!*'();:@&=+$,/?#]/gi))) {
            new_url.push(encode_utf8(url[i]));
//             new_url.push(encodeURIComponent(url[i].charAt(0)));
        }
        else {
            new_url.push(url[i]);
        }
    }
    return new_url.join('');
}
console.log(encodeSymbols('https://ru.wikipedia.org/wiki/Микрокредит'));

//Final result of encoding function
function encodeSymbols (url) {
    var new_url = [];
    for (var i = 0; i < url.length; i++) {
        if(!(url[i].match(/[a-z]|[A-Z]|[0-9]|[!*'();:@&=+$,./?#]/gi))) {
             new_url.push(toUnicode(url[i]));
        }
        else {
            new_url.push(url[i]);
        }
    }
    return new_url.join('');
}

function toUnicode(str){
    var result = "";
    var partial = str.charCodeAt(0).toString(16);
    while(partial.length !== 4) partial = "0" + partial;
    partial = partial.substr(0, 2) + '%' + partial.substr(2, 2) + '%';
    return partial;
};

function encode_utf8 (str) {
    var result = '';
    var symbol = str.charCodeAt(0);

    if(symbol < 128) {
        result =  String.fromCharCode(symbol);
    }
    else if ((symbol > 127) && (symbol < 2048)) {
        console.log(String.fromCharCode((symbol >> 6) | 192));
        result += String.fromCharCode((symbol >> 6) | 192) + '%';
        result += String.fromCharCode((symbol & 63) | 128) + '%';
    }
    return result;
}

console.log(encodeSymbols("https://ru.wikipedia.org/wiki/Микрокредит"));