HTML Encode

HTML Encoding (also known as HTML entity encoding) is the process of converting characters that have special meanings in HTML (such as <, >, &, ", etc.) into their corresponding HTML entities to prevent them from being interpreted as HTML code.

Why HTML Encoding is Needed:
Special Characters in HTML: Certain characters in HTML (like <, >, &, " and ') have specific functions in HTML syntax, and if used directly in text content, they can break the page structure or cause security issues (like Cross-Site Scripting, XSS).
Text Display: When you want to display special characters as regular text, you need to encode them to ensure that the browser doesn't interpret them as HTML tags or attributes.
Common HTML Entities:
Here are some common characters and their corresponding HTML encoded entities:

< → &lt;
> → &gt;
& → &amp;
" → &quot;
' → &apos;
Space → &nbsp;
© → &copy;
Example of HTML Encoding:
Consider the following text:

bash

Hello <b>world</b> & "everyone"
HTML Encoded Version:

php-template

Hello &lt;b&gt;world&lt;/b&gt; &amp; &quot;everyone&quot;
How HTML Encoding Works:
Identify Special Characters: Any character that is reserved or has a special function in HTML needs to be encoded.
Replace Special Characters with HTML Entities: These characters are replaced with the corresponding HTML entity code.
HTML Encoding in Different Programming Languages:
JavaScript:
You can encode HTML entities in JavaScript by using a simple function to convert special characters to their HTML entities:

javascript

function htmlEncode(str) {
var element = document.createElement('div');
if (str) {
element.innerText = str;
element.textContent = str;
}
return element.innerHTML;
}

let encoded = htmlEncode('Hello <b>world</b> & "everyone"');
console.log(encoded); // Outputs: Hello &lt;b&gt;world&lt;/b&gt; &amp; &quot;everyone&quot;
Python:
In Python, you can use the html module to encode HTML entities:

python

import html

text = 'Hello <b>world</b> & "everyone"'
encoded_text = html.escape(text)
print(encoded_text) # Outputs: Hello &lt;b&gt;world&lt;/b&gt; &amp; &quot;everyone&quot;
PHP:
PHP provides the htmlspecialchars() function to convert special characters to HTML entities:

php

$text = 'Hello <b>world</b> & "everyone"';
$encoded_text = htmlspecialchars($text);
echo $encoded_text; // Outputs: Hello &lt;b&gt;world&lt;/b&gt; &amp; &quot;everyone&quot;
When to Use HTML Encoding:
Displaying User Input: When showing text from users (such as in form inputs), encoding it as HTML entities prevents malicious users from injecting HTML or JavaScript code (XSS attacks).
Storing Text: When storing text that may contain special characters (like <, >, &), encoding it can help avoid conflicts with HTML rendering.
Example Use Case:
If you want to include raw HTML content (like <b>hello</b>) in a web page and ensure that it displays as plain text rather than being rendered as bold, you can HTML encode it as &lt;b&gt;hello&lt;/b&gt;.