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Extract hostname name from string

javascript
prompt-engineering
performance
regex
Alex KataevbyAlex Kataev·Nov 19, 2024
TLDR

Here's the speed run: extract the hostname from a URL string using JavaScript's URL object:

const hostname = new URL("http://www.example.com/page").hostname; // "www.example.com"

The hostname property directly pulls out the domain from your URL, simple and effective. Noteworthy: you might need a polyfill for the URL API in older browsers.

Diving deeper: Tackling complexities

The DOM route for hostname

While working with DOM, you might prefer to extract hostnames differently:

function getHostnameFromUrl(url) { var a = document.createElement('a'); a.href = url; return a.hostname; // Viola! You got the hostname }

This alternative approach works well with your jQuery or JavaScript logic dealing with document manipulations.

Handling special unicorns (URLs)

Some URLs are special unicorns with unicode characters and complex TLDs! Here's how you can tame these beasts using the psl npm package:

const psl = require('psl'); // Only for the brave Node.js adventurers! function getDomainFromUrl(url) { let { hostname } = new URL(url); let parsed = psl.parse(hostname); // Train your unicorn! 🦄 return parsed.domain; }

This method shines like a lighthouse guiding ships in an ocean of URLs, effectively handling a variety of URL structures.

Race for performance

When handling large data, the need for performance amplifies. You might want to compare RegExp and URL parsing methods on jsPerf to choose the most efficient one. May the fastest one win!

Regex: A good old friend?

Beyond the URL API, a well-crafted regular expression might help you out:

function extractHostname(url) { const regex = /^(?:https?:\/\/)?(?:www\.)?([^\/\n]+)/i; // I don't always use regex. But when I do, I escape it! const matches = url.match(regex); return matches && matches[1]; // "I found what you're looking for!" }

This regex will gracefully handle protocols (http://, https://) and common subdomains like www. But remember, with great Regex power comes great responsibility: use it wisely!

Browser compatibility considerations

The URL API is not always available, especially in those age-old legacy browsers. You can resort to native string methods like .split and .slice when modern approaches fail.

Custom function: Getting to the root of it

If you are dealing with nuanced requirements such as removing subdomains and only keeping the root domain, create a custom function:

function extractRootDomain(url) { let domain = (new URL(url)).hostname; let parts = domain.split('.').reverse(); // Flip it! if (parts.length > 2) { domain = `${parts[1]}.${parts[0]}`; // Stitching the bits back together! } return domain; // "Here's your treasure!" }