An extensible linter for the TypeScript language.
Supports:
- custom rules
- custom formatters
- inline disabling / enabling of rules
- integration with msbuild, grunt, gulp, atom, eclipse, sublime, vim, visual studio, vscode, webstorm, and more
npm install -g tslint typescript
npm install tslint typescript
typescript
is a peer dependency of tslint
. This allows you to update the compiler independently from the
linter. This also means that tslint
will have to use the same version of tsc
used to actually compile your sources.
Breaking changes in the latest dev release of typescript@next
might break something in the linter if we haven't built against that release yet. If this happens to you, you can try:
- picking up
tslint@next
, which may have some bugfixes not released intslint@latest
(see release notes here). - rolling back
typescript
to a known working version.
Please ensure that the TypeScript source files compile correctly before running the linter.
usage: tslint [options] file ...
Options:
-c, --config configuration file
--force return status code 0 even if there are lint errors
-h, --help display detailed help
-i, --init generate a tslint.json config file in the current working directory
-o, --out output file
-r, --rules-dir rules directory
-s, --formatters-dir formatters directory
-e, --exclude exclude globs from path expansion
-t, --format output format (prose, json, verbose, pmd, msbuild, checkstyle) [default: "prose"]
--test test that tslint produces the correct output for the specified directory
-v, --version current version
By default, configuration is loaded from tslint.json
, if it exists in the current path, or the user's home directory, in that order.
tslint accepts the following command-line options:
-c, --config:
The location of the configuration file that tslint will use to
determine which rules are activated and what options to provide
to the rules. If no option is specified, the config file named
tslint.json is used, so long as it exists in the path.
The format of the file is { rules: { /* rules list */ } },
where /* rules list */ is a key: value comma-seperated list of
rulename: rule-options pairs. Rule-options can be either a
boolean true/false value denoting whether the rule is used or not,
or a list [boolean, ...] where the boolean provides the same role
as in the non-list case, and the rest of the list are options passed
to the rule that will determine what it checks for (such as number
of characters for the max-line-length rule, or what functions to ban
for the ban rule).
-e, --exclude:
A filename or glob which indicates files to exclude from linting.
This option can be supplied multiple times if you need multiple
globs to indicate which files to exclude.
--force:
Return status code 0 even if there are any lint errors.
Useful while running as npm script.
-i, --init:
Generates a tslint.json config file in the current working directory.
-o, --out:
A filename to output the results to. By default, tslint outputs to
stdout, which is usually the console where you're running it from.
-r, --rules-dir:
An additional rules directory, for user-created rules.
tslint will always check its default rules directory, in
node_modules/tslint/lib/rules, before checking the user-provided
rules directory, so rules in the user-provided rules directory
with the same name as the base rules will not be loaded.
-s, --formatters-dir:
An additional formatters directory, for user-created formatters.
Formatters are files that will format the tslint output, before
writing it to stdout or the file passed in --out. The default
directory, node_modules/tslint/build/formatters, will always be
checked first, so user-created formatters with the same names
as the base formatters will not be loaded.
-t, --format:
The formatter to use to format the results of the linter before
outputting it to stdout or the file passed in --out. The core
formatters are prose (human readable), json (machine readable)
and verbose. prose is the default if this option is not used.
Other built-in options include pmd, msbuild, and checkstyle. Additonal
formatters can be added and used if the --formatters-dir option is set.
--test:
Runs tslint on the specified directory and checks if tslint's output matches
the expected output in .lint files. Automatically loads the tslint.json file in the
specified directory as the configuration file for the tests. See the
full tslint documentation for more details on how this can be used to test custom rules.
-v, --version:
The current version of tslint.
-h, --help:
Prints this help message.
var fileName = "Specify file name";
var configuration = {
rules: {
"variable-name": true,
"quotemark": [true, "double"]
}
};
var options = {
formatter: "json",
configuration: configuration,
rulesDirectory: "customRules/", // can be an array of directories
formattersDirectory: "customFormatters/"
};
var Linter = require("tslint");
var fs = require("fs");
var contents = fs.readFileSync(fileName, "utf8");
var ll = new Linter(fileName, contents, options);
var result = ll.lint();
Core rules are included in the tslint
package.
A sample configuration file with all options is available here.
align
enforces vertical alignment. Rule options:"parameters"
checks alignment of function parameters."arguments"
checks alignment of function call arguments."statements"
checks alignment of statements.
ban
bans the use of specific functions. Options are ["object", "function"] pairs that ban the use of object.function().class-name
enforces PascalCased class and interface names.comment-format
enforces rules for single-line comments. Rule options:"check-space"
enforces the rule that all single-line comments must begin with a space, as in// comment
- note that comments starting with
///
are also allowed, for things such as///<reference>
- note that comments starting with
"check-lowercase"
enforces the rule that the first non-whitespace character of a comment must be lowercase, if applicable."check-uppercase"
enforces the rule that the first non-whitespace character of a comment must be uppercase, if applicable.
curly
enforces braces forif
/for
/do
/while
statements.eofline
enforces the file to end with a newline.forin
enforces afor ... in
statement to be filtered with anif
statement.indent
enforces indentation with tabs or spaces. Rule options (one is required):"tabs"
enforces consistent tabs."spaces"
enforces consistent spaces.
interface-name
enforces consistent internace name. Rule options:"always-prefix"
enforces interface names must have an 'I' prefix"never-prefix"
enforces interface name must not have an 'I' prefix
jsdoc-format
enforces basic format rules for jsdoc comments -- comments starting with/**
- each line contains an asterisk and asterisks must be aligned
- each asterisk must be followed by either a space or a newline (except for the first and the last)
- the only characters before the asterisk on each line must be whitespace characters
- one line comments must start with
/**
and end with*/
label-position
enforces labels only on sensible statements.label-undefined
checks that labels are defined before usage.max-line-length
sets the maximum length of a line.member-access
enforces using explicit visibility on class members"check-accessor"
enforces explicit visibility on get/set accessors"check-constructor"
enforces explicit visibility on constructors
member-ordering
enforces member ordering. The first option should be an object with anorder
key. Values fororder
can befields-first
,statics-first
,instance-sandwich
, or a custom order.new-parens
enforces parentheses when invoking a constructor via the new keyword.no-angle-bracket-type-assertion
disallows usages of<>
type assertions in favor of using theas
keyword.no-any
diallows usages ofany
as a type decoration.no-arg
disallows access toarguments.callee
.no-bitwise
disallows bitwise operators.no-conditional-assignment
disallows any type of assignment in any conditionals. This applies todo-while
,for
,if
, andwhile
statements.no-consecutive-blank-lines
disallows having more than one blank line in a row in a file.no-console
disallows access to the specified functions onconsole
. Rule options are functions to ban on the console variable.no-construct
disallows access to the constructors ofString
,Number
, andBoolean
.no-constructor-vars
disallows thepublic
andprivate
modifiers for constructor parameters.no-debugger
disallowsdebugger
statements.no-default-export
disallows default exports in ES6-style modules. Use named exports instead.no-duplicate-key
disallows duplicate keys in object literals.no-duplicate-variable
disallows duplicate variable declarations in the same block scope.no-empty
disallows empty blocks.no-eval
disallowseval
function invocations.no-inferrable-types
disallows explicit type declarations for variables or parameters initialized to a number, string, or boolean.ignore-params
allows specifying an inferrable type as a function param
no-internal-module
disallows internalmodule
(usenamespace
instead).no-invalid-this
disallows using thethis
keyword outside of classes.check-function-in-method
disallows using thethis
keyword in functions within class methods.
no-mergeable-namespace
disallows mergeable namespaces in the same file.no-namespace
disallows both internalmodule
s andnamespace
, but allows ES6-style external modules.allow-declarations
allowsdeclare namespace ... {}
to describe external APIs.
no-null-keyword
disallows use of thenull
keyword literal.no-reference
disallows/// <reference path=>
imports (use ES6-style imports instead).no-require-imports
disallows invocation ofrequire()
(use ES6-style imports instead).no-shadowed-variable
disallows shadowed variable declarations.no-string-literal
disallows object access via string literals.no-switch-case-fall-through
disallows falling through case statements. As of TypeScript version 1.8, this rule can be enabled within the compiler by passing the--noFallthroughCasesInSwitch
flag.no-trailing-whitespace
disallows trailing whitespace at the end of a line.no-unreachable
disallows unreachable code afterbreak
,catch
,throw
, andreturn
statements. This rule is supported and enforced by default within the TypeScript compiler since version 1.8.no-unused-expression
disallows unused expression statements, that is, expression statements that are not assignments or function invocations (and thus no-ops).no-unused-variable
disallows unused imports, variables, functions and private class members. Rule options:"check-parameters"
disallows unused function and constructor parameters.- NOTE: this option is experimental and does not work with classes that use abstract method declarations, among other things. Use at your own risk.
"react"
relaxes the rule for a namespace import namedReact
(from either the module"react"
or"react/addons"
). Any JSX expression in the file will be treated as a usage ofReact
(because it expands toReact.createElement
).{"ignore-pattern": "pattern"}
where pattern is a case-sensitive regexp. Variable names that match the pattern will be ignored.
no-use-before-declare
disallows usage of variables before their declaration.no-var-keyword
disallows usage of thevar
keyword, uselet
orconst
instead.no-var-requires
disallows the use of require statements except in import statements, banning the use of forms such asvar module = require("module")
.object-literal-sort-keys
checks that keys in object literals are declared in alphabetical order (useful to prevent merge conflicts).one-line
enforces the specified tokens to be on the same line as the expression preceding it. Rule options:"check-catch"
checks thatcatch
is on the same line as the closing brace fortry
."check-else"
checks thatelse
is on the same line as the closing brace forif
."check-finally"
checks thatfinally
is on the same line as the closing brace for the precedingtry
orcatch
."check-open-brace"
checks that an open brace falls on the same line as its preceding expression."check-whitespace"
checks preceding whitespace for the specified tokens.
one-variable-per-declaration
disallows multiple variable definitions in the same statement."ignore-for-loop"
allows multiple variable definitions in for loop statement.
quotemark
enforces consistent single or double quoted string literals. Rule options (at least one of"double"
or"single"
is required):"single"
enforces single quotes."double"
enforces double quotes."jsx-single"
enforces single quotes for JSX attributes."jsx-double"
enforces double quotes for JSX attributes."avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
radix
enforces the radix parameter ofparseInt
.semicolon
enforces consistent semicolon usage at the end of every statement. Rule options:"always"
enforces semicolons at the end of every statement."never"
disallows semicolons at the end of every statement except for when they are necessary.
switch-default
enforces adefault
case inswitch
statements.trailing-comma
enforces or disallows trailing comma within array and object literals, destructuring assignment and named imports. Each rule option requires a value of"always"
or"never"
. Rule options:"multiline"
checks multi-line object literals."singleline"
checks single-line object literals.
triple-equals
enforces===
and!==
in favor of==
and!=
."allow-null-check"
allows==
and!=
when comparing tonull
."allow-undefined-check"
allows==
and!=
when comparing toundefined
.
typedef
enforces type definitions to exist. Rule options:"call-signature"
checks return type of functions."parameter"
checks type specifier of function parameters for non-arrow functions."arrow-parameter"
checks type specifier of function parameters for arrow functions."property-declaration"
checks return types of interface properties."variable-declaration"
checks variable declarations."member-variable-declaration"
checks member variable declarations.
typedef-whitespace
enforces spacing whitespace for type definitions. Each rule option requires a value of"nospace"
,"onespace"
or"space"
to require no space, exactly one or at least one space before or after the type specifier's colon. You can specify two objects containing the five options. The first one describes the left, the second one the right hand side of the typedef colon. To omit checks for either side, omit the second object or pass an empty object for the first. Rule options:"call-signature"
checks return type of functions."index-signature"
checks index type specifier of indexers."parameter"
checks function parameters."property-declaration"
checks object property declarations."variable-declaration"
checks variable declaration.
use-isnan
enforces that you use the isNaN() function to check for NaN references instead of a comparison to the NaN constant.use-strict
enforces ECMAScript 5's strict mode.check-module
checks that all top-level modules are using strict mode.check-function
checks that all top-level functions are using strict mode.
variable-name
checks variables names for various errors. Rule options:"check-format"
: allows only camelCased or UPPER_CASED variable names"allow-leading-underscore"
allows underscores at the beginning."allow-trailing-underscore"
allows underscores at the end."allow-pascal-case"
allows PascalCase in addition to camelCase.
"ban-keywords"
: disallows the use of certain TypeScript keywords (any
,Number
,number
,String
,string
,Boolean
,boolean
,undefined
) as variable or parameter names.
whitespace
enforces spacing whitespace. Rule options:"check-branch"
checks branching statements (if
/else
/for
/while
) are followed by whitespace."check-decl"
checks that variable declarations have whitespace around the equals token."check-operator"
checks for whitespace around operator tokens."check-module"
checks for whitespace in import & export statements."check-separator"
checks for whitespace after separator tokens (,
/;
)."check-type"
checks for whitespace before a variable type specification."check-typecast"
checks for whitespace between a typecast and its target.
You may enable/disable TSLint or a subset of rules within certain lines of a file with the following comment rule flags:
/* tslint:disable */
- Disable all rules for the rest of the file/* tslint:enable */
- Enable all rules for the rest of the file/* tslint:disable:rule1 rule2 rule3... */
- Disable the listed rules for the rest of the file/* tslint:enable:rule1 rule2 rule3... */
- Enable the listed rules for the rest of the file// tslint:disable-next-line
- Disables all rules for the following linesomeCode(); // tslint:disable-line
- Disables all rules for the current line// tslint:disable-next-line:rule1 rule2 rule3...
- Disables the listed rules for the next line- etc.
Rules flags enable or disable rules as they are parsed. Disabling an already disabled rule or enabling an already enabled rule has no effect.
For example, imagine the directive /* tslint:disable */
on the first line of a file, /* tslint:enable:ban class-name */
on the 10th line and /* tslint:enable */
on the 20th. No rules will be checked between the 1st and 10th lines, only the ban
and class-name
rules will be checked between the 10th and 20th, and all rules will be checked for the remainder of the file.
If we don't have all the rules you're looking for, you can either write your own custom rules or use custom rules that others have developed. The repos below are a good source of custom rules:
- ESLint rules for TSLint - Improve your TSLint with the missing ESLint Rules
- tslint-microsoft-contrib - A set of TSLint rules used on some Microsoft projects
- codelyzer - A set of tslint rules for static code analysis of Angular 2 TypeScript projects
TSLint ships with a set of core rules that can be configured. However, users are also allowed to write their own rules, which allows them to enforce specific behavior not covered by the core of TSLint. TSLint's internal rules are itself written to be pluggable, so adding a new rule is as simple as creating a new rule file named by convention. New rules can be written in either TypeScript or Javascript; if written in TypeScript, the code must be compiled to Javascript before invoking TSLint.
Rule names are always camel-cased and must contain the suffix Rule
. Let us take the example of how to write a new rule to forbid all import statements (you know, for science). Let us name the rule file noImportsRule.ts
. Rules can be referenced in tslint.json
in their kebab-case forms, so "no-imports": true
would turn on the rule.
Now, let us first write the rule in TypeScript. A few things to note:
- We import
tslint/lib/lint
to get the wholeLint
namespace instead of just theLinter
class. - The exported class must always be named
Rule
and extend fromLint.Rules.AbstractRule
.
import * as ts from "typescript";
import * as Lint from "tslint/lib/lint";
export class Rule extends Lint.Rules.AbstractRule {
public static FAILURE_STRING = "import statement forbidden";
public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
return this.applyWithWalker(new NoImportsWalker(sourceFile, this.getOptions()));
}
}
// The walker takes care of all the work.
class NoImportsWalker extends Lint.RuleWalker {
public visitImportDeclaration(node: ts.ImportDeclaration) {
// create a failure at the current position
this.addFailure(this.createFailure(node.getStart(), node.getWidth(), Rule.FAILURE_STRING));
// call the base version of this visitor to actually parse this node
super.visitImportDeclaration(node);
}
}
Given a walker, TypeScript's parser visits the AST using the visitor pattern. So the rule walkers only need to override the appropriate visitor methods to enforce its checks. For reference, the base walker can be found in syntaxWalker.ts.
We still need to hook up this new rule to TSLint. First make sure to compile noImportsRule.ts
:
tsc -m commonjs --noImplicitAny noImportsRule.ts node_modules/tslint/lib/tslint.d.ts
Then, if using the CLI, provide the directory that contains this rule as an option to --rules-dir
. If using TSLint as a library or via grunt-tslint
, the options
hash must contain "rulesDirectory": "..."
. If you run the linter, you'll see that we have now successfully banned all import statements via TSLint!
Final notes:
- Core rules cannot be overwritten with a custom implementation.
- Custom rules can also take in options just like core rules (retrieved via
this.getOptions()
).
Just like rules, additional formatters can also be supplied to TSLint via --formatters-dir
on the CLI or formattersDirectory
option on the library or grunt-tslint
. Writing a new formatter is simpler than writing a new rule, as shown in the JSON formatter's code.
import * as ts from "typescript";
import * as Lint from "tslint/lib/lint";
export class Formatter extends Lint.Formatters.AbstractFormatter {
public format(failures: Lint.RuleFailure[]): string {
var failuresJSON = failures.map((failure: Lint.RuleFailure) => failure.toJson());
return JSON.stringify(failuresJSON);
}
}
Such custom formatters can also be written in JavaScript. Formatter files are always named with the suffix Formatter
and referenced from TSLint without their suffix.
git clone [email protected]:palantir/tslint.git
npm install
grunt
The next
branch of this repo tracks the latest TypeScript compiler
nightly release as a devDependency
. This allows you to develop the linter and its rules against the latest features of the
language. Releases from this branch are published to npm with the next
dist-tag, so you may install the latest dev
version of TSLint via npm install tslint@next
.
- Bump the version number in
package.json
andsrc/tslint.ts
- Add release notes in
CHANGELOG.md
- Run
grunt
to build the latest sources - Commit with message
Prepare release <version>
- Run
npm publish
- Create a git tag for the new release and push it (see existing tags here)