When you refer to an HTML, JavaScript (JS), and CSS filter, you may be referring to a set of tools that can help you clean up, optimize, or format your code (minification, beautification, etc.). These tools are used for filtering your code to ensure it follows best practices, is properly formatted, or compressed for performance.

Below is a more detailed explanation of how to filter HTML, JavaScript, and CSS using online tools, categorized by their purpose:

1. HTML Filter Tools
a. HTML Minification (Compression)
Minification removes unnecessary whitespace, line breaks, and comments to reduce the size of the HTML file.

HTML Minifier
Minifies your HTML code, removing unnecessary spaces, comments, and line breaks.
How to Use: Paste your HTML, click Minify to compress the HTML code.
HTML Minifier Online
Another tool to remove whitespace, comments, and redundant tags from your HTML file.
How to Use: Paste HTML and click Minify.
b. HTML Formatter (Pretty-Print)
This tool makes HTML more readable by adding indentation and line breaks.

FreeFormatter HTML Formatter
A simple HTML formatter to clean up and pretty-print your code.

How to Use: Paste your HTML code and click Format to make it readable.
HTML Formatter Online
Formats and indents your HTML code for better readability.

How to Use: Paste your HTML and click Format.
2. JavaScript (JS) Filter Tools
a. JavaScript Minification (Compression)
Minification reduces file size by removing unnecessary spaces, comments, and shortening variable names.

JSCompress
Minifies your JavaScript code to make it more efficient for production.

How to Use: Paste the JS code and click Compress to reduce the file size.
UglifyJS Online
Compresses JavaScript with advanced minification options.

How to Use: Paste your JS code and click Uglify to minify it.
b. JavaScript Formatter (Pretty-Print)
Pretty-printing formats JavaScript to make the code readable with proper indentation.

JS Beautifier
Beautifies JavaScript code to make it readable with proper indentation.

How to Use: Paste the JS code and click Beautify to format it.
JavaScript Formatter
Formats JavaScript for readability with indentation and line breaks.

How to Use: Paste the JS code and click Format.
3. CSS Filter Tools
a. CSS Minification (Compression)
Minifying CSS removes unnecessary spaces and comments to make your CSS file smaller and more efficient.

CSS Minifier
Minifies CSS to reduce file size and improve performance.

How to Use: Paste the CSS code and click Minify to compress it.
Clean CSS
Another tool for CSS compression, with options for various minification levels.

How to Use: Paste CSS code and click Minify CSS.
b. CSS Formatter (Pretty-Print)
Pretty-printing CSS makes your stylesheet easier to read and maintain.

CSS Beautifier
Beautifies CSS code by adding indentation and organizing rules.

How to Use: Paste your CSS code and click Beautify to make it readable.
CSS Formatter
Formats your CSS for better readability and consistency.

How to Use: Paste the CSS code and click Format.
4. Combined HTML, CSS, and JS Filters
a. Online Code Beautify
This tool supports HTML, CSS, and JavaScript. It offers options to format or minify your code.

How to Use: Choose the format (HTML, CSS, JS), paste your code, and click Beautify or Minify based on your need.
b. Prettier
Prettier is a popular code formatting tool that supports HTML, CSS, and JavaScript. It ensures consistent formatting across your codebase.

How to Use: Install Prettier on your local system or use it via IDEs. It can be integrated into your development workflow for automatic formatting.
How to Use These Tools for Filtering (Minification & Formatting)
For Minification (Compression):

Paste your HTML, CSS, or JavaScript code into one of the online minification tools.
Click the Minify or Compress button.
Copy the resulting compressed code for use in your production environment.
For Formatting (Pretty-Print):

Paste your code into a formatter tool for HTML, CSS, or JavaScript.
Click Format or Beautify to get the structured, indented version of the code.
Copy the formatted code to make it more readable and easier to edit.
Summary
These filter tools help you:

Minify (compress) HTML, CSS, and JavaScript to reduce file sizes for faster loading.
Format (pretty-print) HTML, CSS, and JavaScript to make the code more readable and maintainable.