原文地址：http://www.jshint.com/docs/options/
This is a complete list of all configuration options accepted by JSHint. If you see something missing, you should either file a bug or email me.
When set to true, these options will make JSHint produce more warnings about your code.
| [bitwise](#bitwise) | This option prohibits the use of bitwise operators such as `^` (XOR), `|` (OR) and others. Bitwise operators are very rare in JavaScript programs and quite often `&` is simply a mistyped `&&`. |
| [camelcase](#camelcase) | This option allows you to force all variable names to use either camelCase style or UPPER_CASE with underscores. |
| [curly](#curly) |
This option requires you to always put curly braces around blocks in loops and
conditionals. JavaScript allows you to omit curly braces when the block consists
of only one statement, for example:
while (day)
shuffle();`
However, in some circumstances, it can lead to bugs (you'd think that `sleep()`
is a part of the loop while in reality it is not):
`while (day)
shuffle();
sleep();` |
| [eqeqeq](#eqeqeq) | This options prohibits the use of `==` and `!=` in favor of `===` and `!==`. The former try to coerce values before comparing them which can lead to some unexpected results. The latter don't do any coercion so they are generally safer. If you would like to learn more about type coercion in JavaScript, we recommend [Truth, Equality and JavaScript](http://javascriptweblog.wordpress.com/2011/02/07/truth-equality-and-javascript/) by Angus Croll. |
| [es3](#es3) | This option tells JSHint that your code needs to adhere to ECMAScript 3 specification. Use this option if you need your program to be executable in older browsers—such as Internet Explorer 6/7/8/9—and other legacy JavaScript environments. |
| [forin](#forin) |
This option requires all `for in` loops to filter object's items. The for in
statement allows for looping through the names of all of the properties of an
object including those inherited throught the prototype chain. This behavior can
lead to unexpected items in your object so it is generally safer to always
filter inherited properties out as shown in the example:
`for (key in obj) {
if (obj.hasOwnProperty(key)) {
// We are sure that obj[key] belongs to the object and was not inherited.
}
}`
For more in-depth understanding of `for in` loops in JavaScript, read
[Exploring JavaScript for-in loops](http://javascriptweblog.wordpress.com/2011/01/04/exploring-javascript-for-in-loops/)
by Angus Croll.
|
| [freeze](#freeze) |
This options prohibits overwriting prototypes of native objects such as
`Array`, `Date` and so on.
`/* jshint freeze:true */
Array.prototype.count = function (value) { return 4; };
// -> Warning: Extending prototype of native object: 'Array'.` |
| [immed](#immed) | This option prohibits the use of immediate function invocations without wrapping them in parentheses. Wrapping parentheses assists readers of your code in understanding that the expression is the result of a function, and not the function itself. |
| [indent](#indent) |
This option enforces specific tab width for your code. For example, the
following code will trigger a warning on line 4:
`/*jshint indent:4 */
if (cond) {
doSomething(); // We used only two spaces for indentation here
}` |
| [latedef](#latedef) | This option prohibits the use of a variable before it was defined. JavaScript has function scope only and, in addition to that, all variables are always moved—or hoisted— to the top of the function. This behavior can lead to some very nasty bugs and that's why it is safer to always use variable only after they have been explicitly defined. Setting this option to "nofunc" will allow function declarations to be ignored. For more in-depth understanding of scoping and hoisting in JavaScript, read [JavaScript Scoping and Hoisting](http://www.adequatelygood.com/2010/2/JavaScript-Scoping-and-Hoisting) by Ben Cherry. |
| [newcap](#newcap) | This option requires you to capitalize names of constructor functions. Capitalizing functions that are intended to be used with `new` operator is just a convention that helps programmers to visually distinguish constructor functions from other types of functions to help spot mistakes when using `this`. Not doing so won't break your code in any browsers or environments but it will be a bit harder to figure out—by reading the code—if the function was supposed to be used with or without new. And this is important because when the function that was intended to be used with `new` is used without it, `this` will point to the global object instead of a new object. |
| [noarg](#noarg) | This option prohibits the use of `arguments.caller` and `arguments.callee`. Both `.caller` and `.callee` make quite a few optimizations impossible so they were deprecated in future versions of JavaScript. In fact, ECMAScript 5 forbids the use of `arguments.callee` in strict mode. |
| [noempty](#noempty) | This option warns when you have an empty block in your code. JSLint was originally warning for all empty blocks and we simply made it optional. There were no studies reporting that empty blocks in JavaScript break your code in any way. |
| [nonbsp](#nonbsp) | This option warns about "non-breaking whitespace" characters. These characters can be entered with option-space on Mac computers and have a potential of breaking non-UTF8 web pages. |
| [nonew](#nonew) |
This option prohibits the use of constructor functions for side-effects. Some
people like to call constructor functions without assigning its result to any
variable:
`new MyConstructor();`There is no advantage in this approach over simply calling `MyConstructor` since the object that the operator `new` creates isn't used anywhere so you should generally avoid constructors like this one. |
| [plusplus](#plusplus) | This option prohibits the use of unary increment and decrement operators. Some people think that `++` and `--` reduces the quality of their coding styles and there are programming languages—such as Python—that go completely without these operators. |
| [quotmark](#quotmark) | This option enforces the consistency of quotation marks used throughout your code. It accepts three values: `true` if you don't want to enforce one particular style but want some consistency, `"single"` if you want to allow only single quotes and `"double"` if you want to allow only double quotes. |
| [undef](#undef) |
This option prohibits the use of explicitly undeclared variables. This option
is very useful for spotting leaking and mistyped variables.
`/*jshint undef:true */
function test() {
var myVar = 'Hello, World';
console.log(myvar); // Oops, typoed here. JSHint with undef will complain
}`
If your variable is defined in another file, you can use `/*global ... */`
directive to tell JSHint about it.
|
| [unused](#unused) |
This option warns when you define and never use your variables. It is very
useful for general code cleanup, especially when used in addition to `undef`.
`/*jshint unused:true */
function test(a, b) {
var c, d = 2;
return a + d;
}
test(1, 2);
// Line 3: 'b' was defined but never used.
// Line 4: 'c' was defined but never used.`
In addition to that, this option will warn you about unused global variables
declared via `/*global ... */` directive.
This can be set to `vars` to only check for variables, not function parameters,
or `strict` to check all variables and parameters. The default (true) behavior
is to allow unused parameters that are followed by a used parameter.
|
| [strict](#strict) | This option requires all functions to run in ECMAScript 5's strict mode. [Strict mode](https://developer.mozilla.org/en/JavaScript/Strict_mode) is a way to opt in to a restricted variant of JavaScript. Strict mode eliminates some JavaScript pitfalls that didn't cause errors by changing them to produce errors. It also fixes mistakes that made it difficult for the JavaScript engines to perform certain optimizations. _Note:_ This option enables strict mode for function scope only. It _prohibits_ the global scoped strict mode because it might break third-party widgets on your page. If you really want to use global strict mode, see the _globalstrict_ option. |
| [trailing](#trailing) |
This option makes it an error to leave a trailing whitespace in your code.
Trailing whitespaces can be source of nasty bugs with multi-line strings in
JavaScript:
`// This otherwise perfectly valid string will error if
// there is a whitespace after \
var str = "Hello \
World";` |
| [maxparams](#maxparams) |
This option lets you set the max number of formal parameters allowed per
function:
`/*jshint maxparams:3 */
function login(request, onSuccess) {
// ...
}
// JSHint: Too many parameters per function (4).
function logout(request, isManual, whereAmI, onSuccess) {
// ...
}` |
| [maxdepth](#maxdepth) |
This option lets you control how nested do you want your blocks to be:
`/*jshint maxdepth:2 */
function main(meaning) {
var day = true;
if (meaning === 42) {
while (day) {
shuffle();
if (tired) { // JSHint: Blocks are nested too deeply (3).
sleep();
}
}
}
}` |
| [maxstatements](#maxstatements) |
This option lets you set the max number of statements allowed per function:
`/*jshint maxstatements:4 */
function main() {
var i = 0;
var j = 0;
// Function declarations count as one statement. Their bodies
// don't get taken into account for the outer function.
function inner() {
var i2 = 1;
var j2 = 1;
return i2 + j2;
}
j = i + j;
return j; // JSHint: Too many statements per function. (5)
}` |
| [maxcomplexity](#maxcomplexity) | This option lets you control cyclomatic complexity throughout your code. Cyclomatic complexity measures the number of linearly independent paths through a program's source code. Read more about [cyclomatic complexity on Wikipedia](http://en.wikipedia.org/wiki/Cyclomatic_complexity). |
| [maxlen](#maxlen) | This option lets you set the maximum length of a line. |
### [Relaxing options](#relaxing-options)
When set to true, these options will make JSHint produce less warnings about your code.
<table class="options table table-bordered table-striped"><tbody><tr>
<td id="asi" class="name">[asi](#asi)</td>
<td class="desc">
This option suppresses warnings about missing semicolons. There is a lot of
FUD about semicolon spread by quite a few people in the community. The
common myths are that semicolons are required all the time (they are not) and
that they are unreliable. JavaScript has rules about semicolons which are
followed by _all_ browsers so it is up to you to decide whether you should or
should not use semicolons in your code.
For more information about semicolons in JavaScript read
[An Open Letter to JavaScript Leaders Regarding Semicolons](http://blog.izs.me/post/2353458699/an-open-letter-to-javascript-leaders-regarding)
by Isaac Schlueter and [JavaScript Semicolon Insertion](http://inimino.org/~inimino/blog/javascript_semicolons).
</td>
</tr>
<tr>
<td id="boss" class="name">[boss](#boss)</td>
<td class="desc">
This option suppresses warnings about the use of assignments in cases where
comparisons are expected. More often than not, code like `if (a = 10) {}` is a
typo. However, it can be useful in cases like this one:
<pre>`for (var i = 0, person; person = people[i]; i++) {}`</pre>
You can silence this error on a per-use basis by surrounding the assignment
with parenthesis, such as:
<pre>`for (var i = 0, person; (person = people[i]); i++) {}`</pre></td>
</tr>
<tr>
<td id="debug" class="name">[debug](#debug)</td>
<td class="desc">
This option suppresses warnings about the `debugger` statements in your code.
</td>
</tr>
<tr>
<td id="eqnull" class="name">[eqnull](#eqnull)</td>
<td class="desc">
This option suppresses warnings about `== null` comparisons. Such comparisons
are often useful when you want to check if a variable is `null` or `undefined`.
</td>
</tr>
<tr>
<td id="esnext" class="name">[esnext](#esnext)</td>
<td class="desc">
This option tells JSHint that your code uses ECMAScript 6 specific syntax.
Note that these features are not finalized yet and not all browsers implement
them.
More info:
Draft Specification for ES.next (ECMA-262 Ed. 6)
This option suppresses warnings about the use of eval. The use of eval is
discouraged because it can make your code vulnerable to various injection
attacks and it makes it hard for JavaScript interpreter to do certain
optimizations.
This option suppresses warnings about the use of expressions where normally you would expect to see assignments or function calls. Most of the time, such code is a typo. However, it is not forbidden by the spec and that's why this warning is optional.
This option suppresses warnings about declaring variables inside of control structures while accessing them later from the outside. Even though JavaScript has only two real scopes—global and function—such practice leads to confusion among people new to the language and hard-to-debug bugs. This is why, by default, JSHint warns about variables that are used outside of their intended scope.
`function test() {
if (true) {
var x = 0;
}
x += 1; // Default: 'x' used out of scope.
// No warning when funcscope:true
}`
This option makes JSHint compatible with Google Closure Compiler.
This option suppresses warnings about the use of global strict mode. Global strict mode can break third-party widgets so it is not recommended.
For more info about strict mode see the strict option.
This option suppresses warnings about the __iterator__ property. This property
is not supported by all browsers so use it carefully.
This option suppresses warnings about missing semicolons, but only when the semicolon is omitted for the last statement in a one-line block:
`var name = (function() { return 'Anton' }());`
This is a very niche use case that is useful only when you use automatic JavaScript code generators.
This option suppresses most of the warnings about possibly unsafe line breakings
in your code. It doesn't suppress warnings about comma-first coding style. To
suppress those you have to use laxcomma (see below).
This option suppresses warnings about comma-first coding style:
`var obj = {
name: 'Anton'
, handle: 'valueof'
, role: 'SW Engineer'
};`
This option suppresses warnings about functions inside of loops. Defining functions inside of loops can lead to bugs such as this one:
`var nums = [];
for (var i = 0; i < 10; i++) {
nums[i] = function (j) {
return i + j;
};
}
nums[0](2); // Prints 12 instead of 2`
To fix the code above you need to copy the value of i:
`var nums = [];
for (var i = 0; i < 10; i++) {
(function (i) {
nums[i] = function (j) {
return i + j;
};
}(i));
}`
This options allows you to set the maximum amount of warnings JSHint will produce before giving up. Default is 50.
This options tells JSHint that your code uses Mozilla JavaScript extensions. Unless you develop specifically for the Firefox web browser you don't need this option.
More info:
This option suppresses warnings about multi-line strings. Multi-line strings
can be dangerous in JavaScript because all hell breaks loose if you accidentally
put a whitespace in between the escape character (\) and a new line.
Note that even though this option allows correct multi-line strings, it still warns about multi-line strings without escape characters or with anything in between the escape character and a whitespace.
`/*jshint multistr:true */ var text = "Hello\ World"; // All good. text = "Hello World"; // Warning, no escape character. text = "Hello\ World"; // Warning, there is a space after \`
This option suppresses warnings about invalid typeof operator values.
This operator has only a limited set of possible return values.
By default, JSHint warns when you compare its result with an invalid
value which often can be a typo.
`// 'fuction' instead of 'function'
if (typeof a == "fuction") { // Invalid typeof value 'fuction'
/* ... */
}`
Do not use this option unless you're absolutely sure you don't want these checks.
This option suppresses warnings about the __proto__ property.
This option suppresses warnings about the use of script-targeted URLs—such as
javascript:....
This option suppresses warnings about mixed tabs and spaces when the latter are used for alignmnent only. The technique is called SmartTabs.
This option suppresses warnings about variable shadowing i.e. declaring a variable that had been already declared somewhere in the outer scope.
This option suppresses warnings about using [] notation when it can be
expressed in dot notation: person['name'] vs. person.name.
This option suppresses warnings about "weird" constructions like
new function () { ... } and new Object;. Such constructions are sometimes
used to produce singletons in JavaScript:
`var singleton = new function() {
var privateVar;
this.publicMethod = function () {}
this.publicMethod2 = function () {}
};`
This option suppresses warnings about possible strict violations when the code
is running in strict mode and you use this in a non-constructor function. You
should use this option—in a function scope only—when you are positive that your
use of this is valid in the strict mode (for example, if you call your
function using Function.call).
Note: This option can be used only inside of a function scope. JSHint will fail with an error if you will try to set this option globally.
This option suppresses warnings about generator functions with no yield statement
in them.
These options let JSHint know about some pre-defined global variables.
| [browser](#browser) | This option defines globals exposed by modern browsers: all the way from good old `document` and `navigator` to the HTML5 `FileReader` and other new developments in the browser world. **Note:** This option doesn't expose variables like `alert` or `console`. See option `devel` for more information. |
| [couch](#couch) | This option defines globals exposed by [CouchDB](http://couchdb.apache.org/). CouchDB is a document-oriented database that can be queried and indexed in a MapReduce fashion using JavaScript. |
| [devel](#devel) | This option defines globals that are usually used for logging poor-man's debugging: `console`, `alert`, etc. It is usually a good idea to not ship them in production because, for example, `console.log` breaks in legacy versions of Internet Explorer. |
| [dojo](#dojo) | This option defines globals exposed by the [Dojo Toolkit](http://dojotoolkit.org/). |
| [jquery](#jquery) | This option defines globals exposed by the [jQuery](http://jquery.com/) JavaScript library. |
| [mootools](#mootools) | This option defines globals exposed by the [MooTools](http://mootools.net/) JavaScript framework. |
| [node](#node) | This option defines globals available when your code is running inside of the Node runtime environment. [Node.js](http://nodejs.org/) is a server-side JavaScript environment that uses an asynchronous event-driven model. This option also skips some warnings that make sense in the browser environments but don't make sense in Node such as file-level `use strict` pragmas and `console.log` statements. |
| [nonstandard](#nonstandard) | This option defines non-standard but widely adopted globals such as `escape` and `unescape`. |
| [phantom](#phantom) | This option defines globals available when your core is running inside of the PhantomJS runtime environment. [PhantomJS](http://phantomjs.org/) is a headless WebKit scriptable with a JavaScript API. It has fast and native support for various web standards: DOM handling, CSS selector, JSON, Canvas, and SVG. |
| [prototypejs](#prototypejs) | This option defines globals exposed by the [Prototype](http://www.prototypejs.org/) JavaScript framework. |
| [rhino](#rhino) | This option defines globals available when your code is running inside of the Rhino runtime environment. [Rhino](http://www.mozilla.org/rhino/) is an open-source implementation of JavaScript written entirely in Java. |
| [worker](#worker) | This option defines globals available when your code is running inside of a Web Worker. [Web Workers](https://developer.mozilla.org/en/Using_web_workers) provide a simple means for web content to run scripts in background threads. |
| [wsh](#wsh) | This option defines globals available when your code is running as a script for the [Windows Script Host](http://en.wikipedia.org/wiki/Windows_Script_Host). |
| [yui](#yui) | This option defines globals exposed by the [YUI](http://yuilibrary.com/) JavaScript framework. |
These options are deprecated and will be removed soon. DO NOT use them.
<
table class="options table table-bordered table-striped">
This option disallows the use of dangling _ in variables. We don't know why
would you need it.
This option allows only one var statement per function. Some people think
that having a single var in a function, at the top of the function, helps
readability. Example (taken from JSLint/JSHint source code):
<
pre>`x.nud = function () { var b, f, i, j, p, seen = {}, t;
b = token.line !== nexttoken.line; if (b) { indent += option.indent; if (nexttoken.from === indent + option.indent) { indent += option.indent; } }
// [...] };
This option makes JSHint stop on the first error or warning.
This option make JSHint check your source code against Douglas Crockford's JavaScript coding style. Unfortunately, his “The Good Parts” book aside, the actual rules are not very well documented.