Our favorite JavaScript trick is a technique for parsing URLs into parts (host, path, query string etc) that doesn’t require any libraries or advanced regular expressions. It uses only the power of the DOM, and the anchor element <a>.
Let us demonstrate:
JS
$(function(){
// The URL we want to parse
var url = 'http://www.ma-no.org/en/content/index_top-12-free-javascript-resources-for-advanced-users-nbsp_1875.php?key=value#comments';
// The magic: create a new anchor element, and set the URL as its href attribute.
// Notice that we are accessing the DOM element inside the jQuery object with [0]:
var a = $('<a>', { href:url } )[0];
$('#host').val(a.hostname);
$('#path').val(a.pathname);
$('#query').val(a.search);
$('#hash').val(a.hash);
// Even more:
// a.port, a.protocol,
// a.origin (not available in older IE versions)
});
HTML
<ul> <li><label for="host">Host:</label> <input type="text" id="host" /></li> <li><label for="path">Path:</label> <input type="text" id="path" /></li> <li><label for="query">Query String:</label> <input type="text" id="query" /></li> <li><label for="hash">Hash:</label> <input type="text" id="hash" /></li> </ul>
CSS
html{
background-color:#f4f4f4;
font:14px/1.4 sans-serif;
color:#666;
}
ul{ list-style:none; width:300px; margin:50px auto; } li{ padding:4px; } input{ font:inherit; border:1px solid #ccc; border-radius:2px; padding:2px 5px; } label{ width:90px; display:inline-block; text-align:right; }
We are using jQuery here but you could use pure JavaScript by creating the anchor element with var a = document.createElement('a'), and then assigning the URL to a.href directly.
Below, another (a bit more) complex example, which lets you type into a textfield and parses the URL in real time:
JS
$(function(){
// Cache the fields
var url = $('#url'), host = $('#host'), path = $('#path'),
query = $('#query'), hash = $('#hash');
// Listen for the input event and update the fields
url.on('input', function(){
var a = $('<a>', { href:url.val() } )[0];
host.val(a.hostname);
path.val(a.pathname);
query.val(a.search);
hash.val(a.hash);
});
// Set a default URL
url.val('http://www.ma-no.org/en/content/index_top-12-free-javascript-resources-for-advanced-users-nbsp_1875.php?key=value#comments');
// Trigger the input event
url.trigger('input');
});
HTML
<div> <label for="url">Enter a URL:</label> <input type="text" id="url" size="50" /> </div> <ul id="parts"> <li><label for="host">Host:</label> <input type="text" id="host" /></li> <li><label for="path">Path:</label> <input type="text" id="path" /></li> <li><label for="query">Query String:</label> <input type="text" id="query" /></li> <li><label for="hash">Hash:</label> <input type="text" id="hash" /></li> </ul>
CSS
html{
background-color:#f4f4f4;
font:14px/1.4 sans-serif;
color:#666;
}
ul{
list-style:none;
width:300px;
margin:0 auto;
}
li{
padding:4px;
}
input{
font:inherit;
border:1px solid #ccc;
border-radius:2px;
padding:2px 5px;
}
label{
width:90px;
display:inline-block;
text-align:right;
}
div{
padding:40px;
text-align:center;
}
The difference here is that we are listening for the input event (not supported in older IEs) which notifies the event listener on every change of the field’s value.
One useful application of this technique is to treat external links differently.
For example, you can add an icon next to each link that points offsite, or you can display some sort of intermediate page that alerts people that they are being redirected to a third party website.
To detect external links, we will compare the hostname properties of the DOM element and the location object:
JS
$(function(){
// Get only the external links:
var external = $('a[href]').filter(function(){
return this.hostname != location.hostname;
});
// In the return above, you may also compare the protocol
// property if you wish to distinguish http from https links.
external.addClass('external');
});
HTML
<a href="?page=123">Page 1</a> <a href="/page2.html">Page 2</a> <a href="http://demo.ma-no.org/">Page 3</a> <a href="http://ma-no.org/page3.html">Page 4</a> <a href="http://google.com/">Page 5</a>
CSS
html{
background-color:#f4f4f4;
font:15px/1.4 sans-serif;
color:#666;
}
body{
padding:50px;
text-align:center;
}
a{
color:#999;
}
a.external{
color:green;
}
a.external:after{
content:'put your icon ';
}