How can i read List items from root site like as: "https://site.sharepoint.com/Lists/ListName"

 I have App part project and i want to read list items from my root site "https://site.sharepoint.com/Lists/ListName"

but after adding app part to wiki page, my codes can't read list and items.

here is my code:

Please help me. Thank in advance.

var web;
var hostweburl;
var appweburl
var namedListItem;


$(document).ready(function () {
    SP.SOD.executeFunc('sp.js', 'SP.ClientContext', sharePointReady);
});


function sharePointReady() {
    hostweburl = decodeURIComponent(getQueryStringParameter('SPHostUrl'));
    appweburl = decodeURIComponent(getQueryStringParameter('SPAppWebUrl'));
    var scriptbase = hostweburl + '/_layouts/15/';
    $.getScript(scriptbase + 'SP.Runtime.js', function () {
        $.getScript(scriptbase + 'SP.js', function () {
            $.getScript(scriptbase + 'SP.RequestExecutor.js', getAllList);
        }
        );
    }
    );

    event.preventDefault();
}

function getQueryStringParameter(param) {
    var params = document.URL.split("?")[1].split("&");
    //var strParams = "";     
    for (var i = 0; i < params.length; i = i + 1) {
        var singleParam = params[i].split("=");
        if (singleParam[0] == param) {
            return singleParam[1];
        }
    }
}

function getAllList() {
    var context;
    var factory;
    var appContextSite;
    var collList;
    context = new SP.ClientContext(appweburl);
    factory = new SP.ProxyWebRequestExecutorFactory(appweburl);
    context.set_webRequestExecutorFactory(factory);
    appContextSite = new SP.AppContextSite(context, hostweburl);
    this.web = appContextSite.get_web();
    collList = this.web.get_lists();
    context.load(collList);
    context.executeQueryAsync(Function.createDelegate(this, successHandler), Function.createDelegate(this, errorHandler));


    function successHandler() {
        try {
            var listInfo = '';
            var listEnumerator = collList.getEnumerator();
            while (listEnumerator.moveNext()) {
                var oList = listEnumerator.get_current();
                if (oList.get_title() == "List Name") {
                    var listItemInfo = '';

                    listItemInfo += '\nID: ' + oListItem.get_id() +
                        '\nTitle: ' + oListItem.get_item('Title') +
                        '\nBody: ' + oListItem.get_item('Body');

                }
                else
                    listInfo += '<li>' + oList.get_title() + '</li>';
            }
            document.getElementById("message").innerHTML = 'Lists found:<ul>' + listInfo + '</ul>';
        }
        catch (error) {
            document.getElementById("message").innerHTML = error.message;
        }
    }

    function errorHandler(sender, args) {
        document.getElementById("message").innerText = "Could not complete cross-domain call: " + args.get_message();

    }
}