autocomplete is not working when geting subsites it dont display

$(document).ready(function () {


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

});

function execCrossDomainRequest() { var executor = new SP.RequestExecutor(appweburl); executor.executeAsync( { url: appweburl + "/_api/SP.AppContextSite(@target)/web/webs?@target='" + hostweburl + "'", method: "GET", headers: { "Accept": "application/json; odata=verbose" }, success: successHandler, error: errorHandler } );

function successHandler(data) {


    var jsonObject = JSON.parse(data.body);
    var results = jsonObject.d.results;
    var result = '';
    for (var i = 1; i < results.length; i++) {
        result = result + results[i].Title;

    }
    $('#tags').autocomplete({
        source: result
    });

}

} function errorHandler(data, errorCode, errorMessage) { document.getElementById("Error").innerText = "Could not complete cross-domain call: " + errorMessage; } function getQueryStringParameter(paramToRetrieve) { 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] == paramToRetrieve) return singleParam[1]; } }