Live search using autocomplete node.js and express.js - node.js

Question

community. I am trying to implement a live search using the autocomplete library but every try is unsuccessful. I get every time a 500 server error. Every assistant is appreciated because I am new in coding.
I have a simple model for an article with title and body and I would like to show suggestions when the user search for an article
model/article.js
// Method to construct the json result set
module.exports.buildResultSet=function(docs) {
var result = [];
for(var object in docs){
result.push(docs[object]);
}
return result;
}
routes/article.js
router.get('/search', function(req, res){
encyclopediaModel.getMyArticlesByName(theRequester, function (pError, pFoundedArticles) {
if (!pError) {
// Method to construct the json result set
var result = encyclopediaModel.buildResultSet(pFoundedArticles);
res.json(result);
} else {
return res.json(JSON.stringify(pError), {
'Content-Type': 'application/json'
}, 404);
}
},req.query.title)
});
//Ajax call
$("#search-query").autocomplete({
source: function (request, response) {
$.ajax({
url: "/encyclopedia/search",
type: "GET",
data: request, // request is the value of search input
success: function (data) {
response( data );
console.log('success', data);
}
});
},
// The minimum number of characters a user must type before a search is performed.
minLength: 3,
// set an onFocus event to show the result on input field when result is focused
focus: function (event, ui) {
this.value = ui.item.label;
// Prevent other event from not being execute
event.preventDefault();
},
select: function (event, ui) {
}
});
<input id="search-query" type="text" placeholder="Articles...">
module.exports.getMyArticlesByName = function (requester, callback, pTitle){
var regex = new RegExp(pTitle["term"], 'i');
article.find({title: regex}, { 'title': 1 }).sort({"updated_at":-1}).sort({"created_at":-1}).limit(20).exec(callback);
}