This document discusses various lint tools for PHP and JavaScript code checking. It describes how lint was originally developed at Bell Labs for C code checking and does static code analysis without execution. For PHP, the built-in php -l command and third party tools like PHPLint are presented. For JavaScript, JSLint is highlighted as a tool that detects obscure errors. The document notes that lint tools find technical errors but not logical errors.

1. LINT
PHP & JavaScript Code Checkers
Lint :: Dave Ross :: Suburban Chicago PHP & Web Design Meetup :: suburbanchicagophp.org :: Sept 3, 2009

2. History of Lint
• Bell Labs, Late 1970s
• First public appearance Unix V7 (1979)
• Written for C language
• Named for bits of crud in sheeps’ wool
Lint :: Dave Ross :: Suburban Chicago PHP & Web Design Meetup :: suburbanchicagophp.org :: Sept 3, 2009

3. Static Code Analysis
• Analyzes code without executing it
• Detects syntax errors (missing semicolons,
missing curly braces)
• Detects some bugs & unsafe code
Lint :: Dave Ross :: Suburban Chicago PHP & Web Design Meetup :: suburbanchicagophp.org :: Sept 3, 2009

4. PHP -l
• PHP’s built-in Lint tool
• Command-line tool
• php -l somefile.php
• Same code PHP uses to parse code at
runtime
Lint :: Dave Ross :: Suburban Chicago PHP & Web Design Meetup :: suburbanchicagophp.org :: Sept 3, 2009

5. PHPLint
• http://www.icosaedro.it/phplint/
• Windows & Unix
Lint :: Dave Ross :: Suburban Chicago PHP & Web Design Meetup :: suburbanchicagophp.org :: Sept 3, 2009

6. PHPLint On-Line
• http://www.icosaedro.it/phplint/phplint-on-line.html
• Only checks one file at a time
• Can’t check dependencies
Lint :: Dave Ross :: Suburban Chicago PHP & Web Design Meetup :: suburbanchicagophp.org :: Sept 3, 2009

7. PHPLint On-Line
Lint :: Dave Ross :: Suburban Chicago PHP & Web Design Meetup :: suburbanchicagophp.org :: Sept 3, 2009

8. JSLint by Doug Crockford
• JavaScript Lint tool
• jslint.com
• “Warning: JSLint will hurt your feelings”
• Detects really obscure JavaScript errors
• See “JavaScript: The Good Parts”
http://www.youtube.com/watch?
v=hQVTIJBZook
Lint :: Dave Ross :: Suburban Chicago PHP & Web Design Meetup :: suburbanchicagophp.org :: Sept 3, 2009

9. Lint :: Dave Ross :: Suburban Chicago PHP & Web Design Meetup :: suburbanchicagophp.org :: Sept 3, 2009

10. Not Psychic
• Lint tools wont find every error
• They’ll find technical errors
• You’re on your own for logical errors
Lint :: Dave Ross :: Suburban Chicago PHP & Web Design Meetup :: suburbanchicagophp.org :: Sept 3, 2009

11. Any Questions?
Dave Ross
PHP & Javascript developer
WordPress plugin developer
http://daveross.tel
http://davidmichaelross.com
Lint :: Dave Ross :: Suburban Chicago PHP & Web Design Meetup :: suburbanchicagophp.org :: Sept 3, 2009