can't add array of strings with concat

Question

I am trying to add some html tags and list as a string to var in javascript. So that I can replace later that code in html.

app.use('/index', function(req, res) {
  var query = req.query;
  var searchQuery = query.search;
  for(i = 0; i < 11; i++){
    if (data[i].indexOf(searchQuery) != -1){
      console.log(data[i]);
      //document.getElementById("".innerHTML = )
     newdata.concat("<li>",data[i],"<li><br>");
      console.log(newdata);
    }
  };
  console.log(newdata);
  var fileContent = fs.readFileSync(path.join(__dirname, '/public/index.html'), "utf8");
  res.send(fileContent.replace("{{data}}", newdata));
});

I am trying to add info to newdata but concat doens't seem to work. Can you please help me and tell me why? I print data before adding to newdata with concat, but after additon newdata is still empty. WHY?

Just in case whole code is here

var express = require('express');
var path = require('path');
var app = express();
var port = process.env.PORT || 3000;
var fs = require ('fs')
var data = ['yellow','mellow','hello','yellow jaws','jaws','jaws 2','jaws 3','mellow jaws','angry jaws','angry jews','angry yellow juice'];
var newdata = '';
app.use(express.static(path.join(__dirname, '/public')));

app.use('/index', function(req, res) {
  var query = req.query;
  var searchQuery = query.search;
  for(i = 0; i < 11; i++){
    if (data[i].indexOf(searchQuery) != -1){
      console.log("VATO");
      console.log(data[i]);
      //document.getElementById("".innerHTML = )
     newdata.concat("<li>",data[i],"<li><br>");
      console.log(newdata);
    }
  };
  console.log(newdata);
  var fileContent = fs.readFileSync(path.join(__dirname, '/public/index.html'), "utf8");
  res.send(fileContent.replace("{{data}}", newdata));
});

app.get('/', function(req, res) {
  res.sendFile(path.join(__dirname, '/public/index.html'));
});

app.listen(port, function() {
  console.log('App is listening on port ' + port);
});

I took down that one and did this one instead. cause that wasn't describing the main problem. — GreedyAi
– GreedyAi, Commented Nov 17, 2015 at 3:50

Victoria French · Accepted Answer · 2015-11-17 04:39:04Z

1

Concat does not modify the original string. It returns the modification. Change this:

newdata.concat("<li>",data[i],"<li><br>");

to

newdata = newdata.concat("<li>",data[i],"</li><br>");

(I also closed the li tag)

answered Nov 17, 2015 at 4:39

Victoria French

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