expomap/static/client/js/rejs/tops.js

(function () {
    "use strict";

    var API_URL_ROOT = "/expo-b/get-tops/";
    var PARENT_ID = "expo_top_events";

    var getUrl = function () {
        var search = [];

        var parts = /^\/([^\/]+)(?:\/|$)/i.exec(location.pathname);
        if (parts) {
            search.push("catalog=" + encodeURIComponent(parts[1]));
        } else {
            search.push("catalog=");
        }

        var data = window.sendData;
        if (data instanceof Object) {
            for (var key in data) {
                if (data.hasOwnProperty(key)) {
                    var value = data[key];

                    if (value instanceof Array) {
                        for (var i = 0, l = value.length; i < l; i++) {
                            search.push(encodeURIComponent(key) + "=" + encodeURIComponent(value[i]));
                        }
                    } else {
                        search.push(encodeURIComponent(key) + "=" + encodeURIComponent(value));
                    }
                }
            }
        }

        return API_URL_ROOT + "?" + search.join("&");
    };

    var getTops = function (url, callback) {
        var xhr = new XMLHttpRequest();
        xhr.open("GET", url, true);

        xhr.onreadystatechange = function (event) {
            if (event.target.readyState === 4) {
                if (event.target.status === 200) {
                    try {
                        callback(event.target.responseText);
                    } catch (error) {
                        // do nothing
                    }
                }
            }
        };

        xhr.send();
    };

    var insertTops = function (text) {
        var parent = document.getElementById(PARENT_ID);

        if (parent) {
            parent.innerHTML = text;
        }
    };

    var main = function () {
        getTops(getUrl(), insertTops);
    };

    window.addEventListener("load", main);
})();