How to escape hash character in URL

Importance of URL hygiene: escaping special characters

Ever heard of URL etiquette? Particular characters, namely special characters like #, can be troublemakers in a URL. Left to their devices, they can incite mishandled behavior. Instead of simply being jolly useful data, #, typically signifies a fragment identifier and tells the browser to hop to a certain spot on the page. Naughty hash.

Worry not, though. You can promote its good behavior by turning the # into a responsible %23 when it's time for it to be a part of the query string or just be data in the URL. Good going, hash. This way, you maintain URL integrity and ensure the server gets the right parameters.

Hash behavior in different environments

Picture PHP, a server-side language. You summon query string parameters with $_GET. Suppose you have a disobedient hash symbol not escaped. That means the parameter retrieval could go haywire:

// No escape, hash causes mischief
echo $_GET['section']; // Doesn't output anything if URL has "#intro"

// Escape to the rescue, hash well-behaved
echo $_GET['section']; // "Intro" gets output if URL ends with "?section=%23intro", #ChampionHash 🏆
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Same goes for frameworks like Angular, React, or other Single Page Application (SPA) setups. You may rely heavily on URL routing. In that case, escaping helps prevent your routing mechanics from going haywire due to this disruptive hash!

Dealing with a handful: multiple special characters

Got more special characters to include in the URL? Use encodeURIComponent for each parameter individually. This function's smart enough to skip already encoded characters while encoding the rest:

let param1 = encodeURIComponent("value#with#hashes");
let param2 = encodeURIComponent("another&value");
let url = `http://example.com/page?param1=${param1}&param2=${param2}`;
// Result: Fully formed and encoded URL, who's a good URL? You're a good URL! 🐶
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Don't forget to decode the parameters on the server side or in JavaScript using decodeURIComponent to retrieve the original values.

Pitfalls and how to dodge 'em

Keen on anchor tags <a>? Keep an eye out for unencoded hashes within them. They can trigger unwanted navigation or harm user experience. Escaping the hash ensures it counts as data, not a URL fragment.

Yo Angular developers! You know how your framework loves using the hash for client-side routing? Unescaped characters could send your navigation for a toss, so watch out!

The HTML form effect and hashes

For instance, consider an HTML form: If a hash character sneaks its way into a text input and gets submitted as part of a GET form, we need proper encoding to safeguard the submission integrity.

<form action="http://example.com/search" method="GET">
  <input type="text" name="query" value="topic#section">
  <!-- Browser sneakily makes the hash turn into %23 upon submission -->
  <button type="submit">Search</button>
</form>
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Behind the scenes of automatic hash encoding

During the form submission process, the browser slyly changes the hash into %23 when piecing together the data to be sent in a GET request. Thus, any special characters get translated into a format compatible with an HTTP request.

Techie decoded: Percent-encoding reference

Every character corresponds to a hexadecimal value in the ASCII character set. For instance, the hash symbol # dishes up 23 in hexadecimal. Therefore, its percent-encoded form is %23. Nifty, isn't it?