Location.host vs location.hostname and cross-browser compatibility?

When to wield location.host and location.hostname

The choice between location.host and location.hostname is dictated by the requirement at hand. For domain validation needs or security checks based on domain, location.hostname is your knight in shining armor. When it comes to situations requiring port number (networking apps, dev environments), location.host pulls its weight.

Take extra caution when you're performing security-sensitive domain checking. Regular expressions like /(^|\.)domain\.com$/ are our best buddies to prevent your app from getting confused with similar domain names (nobody wants to go to fakeamazon.com instead of amazon.com, eh?).

For full URL retrieval, window.location.origin comes to your rescue in modern browsers. However, regarding older Internet Explorer versions, you might need to press the hardwork button and format manually using protocols, hostname, and ports.

Comparing legacy and modern browsers

To ensure your application is the Absolutely Everybody of the Internet, you need to take into account compatibility with various browsers. Luckily, both location.host and location.hostname are like Old Friends; been there since Internet Explorer 6 and play nice with modern browsers too.

Don't just assume URLs will always behave as expected. Proxies and other network shenanigans can modify the metrics of URL properties. Suit up and employ additional checks if some Johnny Proxy tries to interfere.

Minding the pitfalls

Beware of phishing attempts and similarly named domains. Prevent these hijinks with tight validation.

For once, window.location.origin isn't the superhero it is in modern browsers; IE10 and previous versions give it the cold shoulder. In these cases, you might need to summon all your manual concatenation powers with window.location.protocol, window.location.hostname, and window.location.port.

Remember, security isn't a game (well, unless you're a hacker). Don't compromise on the wall of server-side validation while utilizing these URL-centric checks. They're your loyal sidekicks, not the main heroes of your security story.