Search in App web using REST API in SharePoint 2013

<%-- The following 4 lines are ASP.NET directives needed when using SharePoint components --%>

    <%@ Page Inherits="Microsoft.SharePoint.WebPartPages.WebPartPage, Microsoft.SharePoint, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" MasterPageFile="~masterurl/default.master" Language="C#" %>

        <%@ Register TagPrefix="Utilities" Namespace="Microsoft.SharePoint.Utilities" Assembly="Microsoft.SharePoint, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
            <%@ Register TagPrefix="WebPartPages" Namespace="Microsoft.SharePoint.WebPartPages" Assembly="Microsoft.SharePoint, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>
                <%@ Register TagPrefix="SharePoint" Namespace="Microsoft.SharePoint.WebControls" Assembly="Microsoft.SharePoint, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

                    <%-- The markup and script in the following Content element will be placed in the <head> of the page --%>
                        <asp:Content ContentPlaceHolderID="PlaceHolderAdditionalPageHead" runat="server">
                            <script type="text/javascript" src="../Scripts/jquery-1.9.1.min.js"></script>
                            <script type="text/javascript" src="/_layouts/15/sp.runtime.js"></script>
                            <script type="text/javascript" src="/_layouts/15/sp.js"></script>
                            <meta name="WebPartPageExpansion" content="full" />

                            <!-- Add your CSS styles to the following file -->
                            <link rel="Stylesheet" type="text/css" href="../Content/App.css" />

                            <!-- Add your JavaScript to the following file -->
                            <script type="text/javascript" src="../Scripts/App.js"></script>
                        </asp:Content>

                        <%-- The markup in the following Content element will be placed in the TitleArea of the page --%>
                            <asp:Content ContentPlaceHolderID="PlaceHolderPageTitleInTitleArea" runat="server">
                                Page Title
                            </asp:Content>

                            <%-- The markup and script in the following Content element will be placed in the <body> of the page --%>
                                <asp:Content ContentPlaceHolderID="PlaceHolderMain" runat="server">

                                    <div>
                                        <p id="message">
                                            <!-- The following content will be replaced with the user name when you run the app - see App.js -->
                                            initializing...
                                        </p>
                                    </div>

                                    <!-- App Web Search-->
                                    <div id="searchDiv">
                                        <b>Search For</b>
                                        <input type="text" id="txtSearchTerm" />
                                        <input type="button" id="btnSearch" value="Search" onclick="searchAppWeb()" />
                                    </div>
                                    <div id="SearchResultsDiv"></div>
                                    <!--Search Ends-->

                                </asp:Content>

'use strict';

var context = SP.ClientContext.get_current();
var user = context.get_web().get_currentUser();

// This code runs when the DOM is ready and creates a context object which is needed to use the SharePoint object model
$(document).ready(function() {
    getUserName();
});

// This function prepares, loads, and then executes a SharePoint query to get the current users information
function getUserName() {
    context.load(user);
    context.executeQueryAsync(onGetUserNameSuccess, onGetUserNameFail);
}

// This function is executed if the above call is successful
// It replaces the contents of the 'message' element with the user name
function onGetUserNameSuccess() {
    $('#message').text('Hello ' + user.get_title());
}

// This function is executed if the above call fails
function onGetUserNameFail(sender, args) {
    alert('Failed to get user name. Error:' + args.get_message());
}

//Search Implemenatation in App Web using Search REST API
//Do not forget to provide Search Permission in AppManifest file
var html;

function searchAppWeb() {

    //Get the Search Term from textbox
    var searchTerm = $("#txtSearchTerm").val();

    //REST API query URL
    var queryUrl = _spPageContextInfo.webAbsoluteUrl + "/_api/search/query?querytext='" + searchTerm + "'";;

    //Empty the string
    html = "";

    //Make the ajax call
    $.ajax({
        url: queryUrl,
        method: "GET",
        headers: {
            "Accept": "application/json; odata=verbose"
        },
        success: onSearchSuccess,
        error: onSearchError
    });
}

function onSearchSuccess(data) {
    // JSON object contains two elements which have search results
    //1. PrimaryQueryResult
    //2. SecondaryQueryResults (When documents are grouped on Host Web)

    //Get PrimaryQueryResult and Render it in HTML Table format
    html = "<table>";

    var primaryQueryResult = data.d.query.PrimaryQueryResult.RelevantResults.Table.Rows.results;

    if (primaryQueryResult != null && primaryQueryResult != undefined) {
        for (var iPrimaryResultCounter = 0; iPrimaryResultCounter < primaryQueryResult.length; iPrimaryResultCounter++) {
            html += "<tr><td>";
            html += primaryQueryResult[iPrimaryResultCounter].Cells.results[3].Value;
            html += "</td><td><a href=\""
            html += primaryQueryResult[iPrimaryResultCounter].Cells.results[6].Value;
            html += "\">" + primaryQueryResult[iPrimaryResultCounter].Cells.results[6].Value + "</a></td><tr>";
        }
    }

    //Get SecondaryQueryResults and continue rendering it in HTML Table format
    var secondaryResult = data.d.query.SecondaryQueryResults;
    if (data.d.query.SecondaryQueryResults != null && data.d.query.SecondaryQueryResults != undefined) {
        for (var iSecondaryResultCounter = 0; iSecondaryResultCounter < data.d.query.SecondaryQueryResults.results.length; iSecondaryResultCounter++) {
            var resultBlock = data.d.query.SecondaryQueryResults.results[iSecondaryResultCounter].RelevantResults.Table.Rows.results;
            for (var iResults = 0; iResults < resultBlock.length; iResults++) {
                html += "<tr><td>";
                html += resultBlock[iResults].Cells.results[3].Value;
                html += "</td><td><a href=\""
                html += resultBlock[iResults].Cells.results[6].Value;
                html += "\">" + resultBlock[iResults].Cells.results[6].Value + "</a></td><tr>";
            }
        }
    }
    html += "</table>";
    $("#SearchResultsDiv").append(html);

}

function onSearchError(err) {
    alert(JSON.stringify(err));
}