JSHint/JSLint

Static code analysis for JavaScript

Máté FARKAS
Budapest.js, 14/02/2012

Lint

Introduced for the C language
in later 70's
primitive compilers,
common mistakes
static code analysis needed

JSLint

Created by
Douglas Crockford

YUI videos

JavaScript: The Good Parts

“The JavaScript Code Quality Tool”

First release: 2002

De facto standard for
good quality JS code

But there are alternatives, too: Doctor JS, Closure Linter, JavaScriptLint

MIT license

in 12/11/2010 moved to GitHub…

…then a new story began

JSHint

Forked by Anton Kovalyov
at 19/01/2011, because

“[JSLint] is quickly transforming from a tool that helps developers to prevent bugs to a tool that makes sure you write your code like Douglas Crockford.”

“Warning! JSLint will hurt your feelings.”

versus JSHint:

“Our goal is to help JavaScript developers write complex programs without worrying about typos and language gotchas.”

JSLint “The JavaScript Code Quality Tool”, while JSHint is

„A JavaScript Code Quality Tool”

„The (Gentler) JavaScript Code Quality Tool”

„A Static Code Analysis Tool for JavaScript”

Contributors

JSLint: Douglas Crockford
(231 commits)

JSHint: 30+ including Wolfgang Kluge, Josh Perez, Douglas Crockford, Nicholas C. Zakas, Máté Farkas, etc., nearly 400 commits.

Enforcing options

bitwise: bitwise operators (|, &)

curly: curly braces around blocks in loops and conditionals

eqeqeq: use === and !==

forin: requires obj.hasOwnProperty check

immed: immediate function invocations only with wrapping parentheses

latedef: define the variable before using it

newcap: capitalize names of constructor functions

noarg: don't use arguments.caller, arguments.callee

noempty: don't use empty blocks

nonew: constructor functions must not have side effects

plusplus: don't use ++ and --

regexp: don't use '.' in regular expressions

undef: define all variables explicitly

strict: all functions must run in strict mode

trailing: don't put trailing whitespaces in your code

Relaxing Options

asi: allow missing semicolons

boss: allow assignments instead of comparisons

debug: allow debugger statements

eqnull: allow == null

es5: allow es5 features

evil: allow eval

expr: allow use expression instead of assignment or function call

funcscope: allow access to a variable ouside of its scope

globalstrict: allow global "use strict"

iterator: allow use of __iterator__ property

lastsemic: allow missing last semicolon

laxbreak: allow unsafe line breakings

laxcomma: allow comma-first coding style

loopfunc: allow functions inside loops

multistr: allow multiline strings

onecase: allow switch with only one case

proto: allow __proto__ property

regexdash: allow unescaped - in regular expressions

scripturl: allow script-targeted urls

smarttabs: allow tabs + spaces indentation

validthis: allow use of this in a non-constructor function in strict mode

Environments

browser: document, navigator, etc.

couch: CouchDB global variables

devel: console, alert

dojo: Dojo Toolkit global variables

jquery: jQuery global variables

mootols: MooTools global variables

node: Node.js environment

nonstandard: widely adopted non standard globals

prototypejs: Prototype global variables

rhino: Rhino environment

wsh: Windows Scripting Host

Legacy

nomen: allow dangling '_' in variables

onevar: allow only one var statement

passfail: stop on the first error or warning

white: enforce Douglas Crockford's coding style

Integration

Environments: Node.js, WSH, JavaScriptCore, Rhino

Editors: VIM, Emacs, Sublime Text 2, TextMate, Visual Studio, ShiftEdit, Komodo, Eclipse…

Easy to integrate with CI (Jenkins)

Lint or Hint?

JSLint: for generated code (CoffeeScript)

JSHint: for everything else

…or…

have the full control of the source code with a consistent coding style.