How to search for all subsites title and url using Rest

Hi i have a autocomplete search box when typing in my box i want to display the title of the subsite and also url

here is my search box

  <div id="searchfield">
  <input type="text" name="currency" class="biginput" id="autocomplete"/>
  </div>

Here is my code i app.js right now nothing gets displayed, event if i have an subsite named SubSite1

'use strict';

var hostweburl; var appweburl;

// 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 () {

//Get the URI decoded URLs.   
hostweburl =
    decodeURIComponent(
        getQueryStringParameter("SPHostUrl"));
appweburl =
    decodeURIComponent(
        getQueryStringParameter("SPAppWebUrl"));
// Resources are in URLs in the form:  
// web_url/_layouts/15/resource  
var scriptbase = hostweburl + "/_layouts/15/";

// Load the js file and continue to load the page with information about the list top level folders.  
// SP.RequestExecutor.js to make cross-domain requests  

// Load the js files and continue to the successHandler  
$.getScript(scriptbase + "SP.RequestExecutor.js", execCrossDomainRequest);

}); function execCrossDomainRequest() {

// executor: The RequestExecutor object

// Initialize the RequestExecutor with the app web URL.

var executor = new SP.RequestExecutor(appweburl);

// Issue the call against the app web.

// To get the title using REST we can hit the endpoint:

// The response formats the data in the JSON format.  
// The functions successHandler and errorHandler attend the  
//      sucess and error events respectively.  
executor.executeAsync(  

{

url:

appweburl +

"/_api/SP.AppContextSite(@target)/web/webs?@target='" +

hostweburl + "'",

method: "POST",

headers: { "Accept": "application/json; odata=verbose" },

success: function (data) {

    var subsite= JSON.stringify(data);
    $('#autocomplete').autocomplete({
        lookup: subsite,
    })
    } 

} );

}

// This function prepares, loads, and then executes a SharePoint query to get

// the current users information

//Utilities

// Retrieve a query string value.

// For production purposes you may want to use

// a library to handle the query string.

function getQueryStringParameter(paramToRetrieve) {

var params =

document.URL.split("?")[1].split("&");

for (var i = 0; i < params.length; i = i + 1) {

var singleParam = params[i].split("=");

if (singleParam[0] == paramToRetrieve)

return singleParam[1];

}

}