How can I get the title of a webpage given the url (an external url) using JQuery/JS

Something like this should work:

$.ajax({
  url: externalUrl,
  async: true,
  success: function(data) {
    var matches = data.match(/<title>(.*?)<\/title>/);
    alert(matches[0]);
  }   
});

TheSuperTramp is correct, above will not work if externalUrl is outside of your domain. Instead create this php file get_external_content.php:

<?php
function file_get_contents_curl($url){
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
    $data = curl_exec($ch);
    curl_close($ch);
    return $data;
}

$url = $_REQUEST["url"];
$html = file_get_contents_curl($url);

preg_match('/<title>(.+)<\/title>/',$html,$matches);
$title = $matches[1];

echo  json_encode(array("url" => $url, "title" => $title));

---

then in javascript:

function getTitle(externalUrl){
  var proxyurl = "http://localhost/get_external_content.php?url=" + externalUrl;
  $.ajax({
    url: proxyurl,
    async: true,
    success: function(response) {
      alert(response);
    },   
    error: function(e) {
      alert("error! " + e);
    }
  });
}

You can also get the title of any webpage using this API

http://textance.herokuapp.com/title/

$.ajax({
      url: "http://textance.herokuapp.com/title/www.bbc.co.uk",
      complete: function(data) {
        alert(data.responseText);
      }
});

Crossdomain request don't work with ajax, but what you could do is write a script on your server that fetch the title of a given site.

If you are using PHP you could use the file_get_contents and preg_match function to get the title. This guy here already provide the code for it.

http://www.cafewebmaster.com/php-get-page-title-function

Then in jQuery you could add this to an event or put it inside a function.

//For the purpose of this example let's use google
var url = "http://www.google.com";

$.ajax({
  type: "POST",
  url: "./getURLTitle.php",
  data: "{url: \"" + url + "\"}",
  success: function(data) {
     //do stuff here with the result
     alert(data);
  }   
});