How to read and understand encapsulated code [closed]

Your code is #, you can use JS Beautifier to make it readable:

window.Gantt = {
        _seed: 0
    }, Gantt.plugin = function(t) {
        this._ganttPlugin.push(t), t(window.gantt)
    }, Gantt._ganttPlugin = [], Gantt.getGanttInstance = function() {
        var t = {
            version: "4.1.0"
        };
        t = {
                version: "4.1.0"
            }, t.event = function(t, e, i) {
                t.addEventListener ? t.addEventListener(e, i, !1) : t.attachEvent && t.attachEvent("on" + e, i)
            }, t.eventRemove = function(t, e, i) {
                t.removeEventListener ? t.removeEventListener(e, i, !1) : t.detachEvent && t.detachEvent("on" + e, i)
            }, t._eventable = function(t) {
                t._silent_mode = !1, t._silentStart = function() {
                    this._silent_mode = !0;
                }, t._silentEnd = function() {
                    this._silent_mode = !1
                }, t.attachEvent = function(t, e, i) {
                    return t = "ev_" + t.toLowerCase(), this[t] || (this[t] = new this._eventCatcher(i || this)), t + ":" + this[t].addEvent(e)
                }, t.callEvent = function(t, e) {
                    return this._silent_mode ? !0 : (t = "ev_" + t.toLowerCase(), this[t] ? this[t].apply(this, e) : !0)
                }, t.checkEvent = function(t) {
                    return !!this["ev_" + t.toLowerCase()]
                }, t._eventCatcher = function(t) {
                    var e = [],
                        i = function() {
                            for (var i = !0, n = 0; n < e.length; n++)
                                if (e[n]) {
                                    var a = e[n].apply(t, arguments);
                                    i = i && a
                                }
                            return i
                        };
                    return i.addEvent = function(t) {
                        return "function" == typeof t ? e.push(t) - 1 : !1
                    }, i.removeEvent = function(t) {
                        e[t] = null
                    }, i
                }, t.detachEvent = function(t) {
                    if (t) {
                        var e = t.split(":");
                        this[e[0]].removeEvent(e[1])
                    }
                }, t.detachAllEvents = function() {
                    for (var t in this) 0 === t.indexOf("ev_") && delete this[t]
                }, t = null
            }, t.copy = function(e) {
                var i, n, a;
                if (e && "object" == typeof e) {
                    for (a = {}, n = [Array, Date, Number, String, Boolean], i = 0; i < n.length; i++) e instanceof n[i] && (a = i ? new n[i](e) : new n[i]);
                    for (i in e) Object.prototype.hasOwnProperty.apply(e, [i]) && (a[i] = t.copy(e[i]))
                }
                return a || e
            }, t.mixin = function(t, e, i) {
                for (var n in e)(!t[n] || i) && (t[n] = e[n]);
                return t
            }, t.defined = function(t) {
                return "undefined" != typeof t
            }, t.uid = function() {
                return this._seed || (this._seed = (new Date).valueOf()), this._seed++, this._seed
            }, t.bind = function(t, e) {
                return t.bind ? t.bind(e) : function() {
                    return t.apply(e, arguments)
                }
            },
            function() {
                function e(t) {
                    var e = !1,
                        i = !1;
                    if (window.getComputedStyle) {
                        var n = window.getComputedStyle(t, null);
                        e = n.display, i = n.visibility
                    } else t.currentStyle && (e = t.currentStyle.display, i = t.currentStyle.visibility);
                    return "none" != e && "hidden" != i
                }

                function i(t) {
                    return !isNaN(t.getAttribute("tabindex")) && 1 * t.getAttribute("tabindex") >= 0
                }

                function n(t) {
                    var e = {
                        a: !0,
                        area: !0
                    };
                    return e[t.nodeName.loLowerCase()] ? !!t.getAttribute("href") : !0
                }

                function a(t) {
                    var e = {
                        input: !0,
                        select: !0,
                        textarea: !0,
                        button: !0,
                        object: !0
                    };
                    return e[t.nodeName.toLowerCase()] ? !t.hasAttribute("disabled") : !0
                }
                t._getFocusableNodes = function(t) {
                    for (var s = t.querySelectorAll(["a[href]", "area[href]", "input", "select", "textarea", "button", "iframe", "object", "embed", "[tabindex]", "[contenteditable]"].join(", ")), r = Array.prototype.slice.call(s, 0), o = 0; o < r.length; o++) {
                        var _ = r[o],
                            l = (i(_) || a(_) || n(_)) && e(_);
                        l || (r.splice(o, 1), o--)
                    }
                    return r
                }
            }(), t._get_position = function(t) {
                var e = 0,
                    i = 0;
                if (t.getBoundingClientRect) {
                    var n = t.getBoundingClientRect(),
                        a = document.body,
                        s = document.documentElement,
                        r = window.pageYOffset || s.scrollTop || a.scrollTop,
                        o = window.pageXOffset || s.scrollLeft || a.scrollLeft,
                        _ = s.clientTop || a.clientTop || 0,
                        l = s.clientLeft || a.clientLeft || 0;
                    return e = n.top + r - _, i = n.left + o - l, {
                        y: Math.round(e),
                        x: Math.round(i),
                        width: t.offsetWidth,
                        height: t.offsetHeight
                    }
                }
                for (; t;) e += parseInt(t.offsetTop, 10),