simple routes in js

gistfile1.js

    const varRegex = /:([a-zA-Z][a-zA-Z0-9]*)/g;
    function Route(template) {
        this.pack = function pack(data) {
            const varRegexClone = new RegExp(varRegex);
            return template.replace(varRegex, function (m) {
                const key = varRegexClone.exec(m)[1];
                varRegexClone.lastIndex = 0; // resetting regex object
                return data[key];
            });
        };
        this.unpack = function unpack(str) {
            const regex = new RegExp(template.replace(varRegex, '([a-z0-9]+)'));
            const match = regex.exec(str);
            if (!match) {
                return null;
            }
            const vars = [];
            while (true) {
                const m = varRegex.exec(template);
                if (!m) {
                    break;
                }
                vars.push(m[1]);
            }
            return _.zipObject(vars, match.splice(1));
        };
    }
    const r = new Route('/path/:param1/:param2/');
    console.log(r.pack({param1: 'aaa', param2: 1234});
    console.log(r.unpack('/path/bbb/5678/');