ESLint rules for TSLint

Improve your TSLint with the missing ESLint Rules

You want to code in TypeScript but miss all the rules available in ESLint?

Now you can combine both worlds by using this TSLint plugin!

Usage

Install from NPM to your Dev Dependencies

npm install --save-dev tslint-eslint-rules

Configure TSLint to use tslint-eslint-rules folder:

In your tslint.json file, add the rulesDirectory property, e.g:

{
  "rulesDirectory": "node_modules/tslint-eslint-rules/dist/rules",
  "rules": {
    "no-constant-condition": true
  }
}

You can also pass an array of strings to the rulesDirectory property to combine this plugin with other community custom rules.

Configure your rules

In your tslint.json file, insert the rules as described below.

Rules (copied from the ESLint website)

The following tables shows all the existing ESLint rules and the similar rules available in TSLint. Please refer to the following icons as they provide the status of the rule.

Icon	Description
🚫	The rule is not applicable to Typescript.
☑️	The rule is provided natively by TSLint.
✅	The rule is available via tslint-eslint-rules.
❌	The rule is currently unavailable.

Possible Errors

The following rules point out areas where you might have made mistakes.

❔	ESLint	TSLint	Description
☑️	comma-dangle	trailing-comma	disallow or enforce trailing commas (recommended)
☑️	no-cond-assign	no-conditional-assignment	disallow assignment in conditional expressions (recommended)
☑️	no-console	no-console	disallow use of console in the node environment (recommended)
✅	no-constant-condition	no-constant-condition	disallow use of constant expressions in conditions (recommended)
✅	no-control-regex	no-control-regex	disallow control characters in regular expressions (recommended)
☑️	no-debugger	no-debugger	disallow use of debugger (recommended)
🚫	no-dupe-args	Not applicable	disallow duplicate arguments in functions (recommended)
☑️	no-dupe-keys	no-duplicate-key	disallow duplicate keys when creating object literals (recommended)
✅	no-duplicate-case	no-duplicate-case	disallow a duplicate case label. (recommended)
☑️	no-empty	no-empty	disallow empty statements (recommended)
✅	no-empty-character-class	no-empty-character-class	disallow the use of empty character classes in regular expressions (recommended)
✅	no-ex-assign	no-ex-assign	disallow assigning to the exception in a catch block (recommended)
✅	no-extra-boolean-cast	no-extra-boolean-cast	disallow double-negation boolean casts in a boolean context (recommended)
❌	no-extra-parens	no-extra-parens	disallow unnecessary parentheses
✅	no-extra-semi	no-extra-semi	disallow unnecessary semicolons (recommended)
🚫	no-func-assign	Not applicable	disallow overwriting functions written as function declarations (recommended)
✅	no-inner-declarations	no-inner-declarations	disallow function or variable declarations in nested blocks (recommended)
✅	no-invalid-regexp	no-invalid-regexp	disallow invalid regular expression strings in the RegExp constructor (recommended)
✅	no-irregular-whitespace	no-irregular-whitespace	disallow irregular whitespace outside of strings and comments (recommended)
🚫	no-negated-in-lhs	Not applicable	disallow negation of the left operand of an in expression (recommended)
🚫	no-obj-calls	Not applicable	disallow the use of object properties of the global object (Math and JSON) as functions (recommended)
✅	no-regex-spaces	no-regex-spaces	disallow multiple spaces in a regular expression literal (recommended)
✅	no-sparse-arrays	no-sparse-arrays	disallow sparse arrays (recommended)
✅	no-unexpected-multiline	no-unexpected-multiline	Avoid code that looks like two expressions but is actually one
☑️	no-unreachable	no-unreachable	disallow unreachable statements after a return, throw, continue, or break statement (recommended)
✅	use-isnan	use-isnan	disallow comparisons with the value NaN (recommended)
✅	valid-jsdoc	valid-jsdoc	Ensure JSDoc comments are valid
✅	valid-typeof	valid-typeof	Ensure that the results of typeof are compared against a valid string (recommended)

Best Practices

These are rules designed to prevent you from making mistakes. They either prescribe a better way of doing something or help you avoid footguns.

❔	ESLint	TSLint	Description
❌	accessor-pairs	accessor-pairs	Enforces getter/setter pairs in objects
❌	array-callback-return	array-callback-return	Enforce return statements in callbacks of array’s methods
❌	block-scoped-var	accessor-pairs	treat var statements as if they were block scoped
❌	complexity	complexity	specify the maximum cyclomatic complexity allowed in a program
❌	consistent-return	consistent-return	require return statements to either always or never specify values
☑️	curly	curly	specify curly brace conventions for all control statements
☑️	default-case	switch-default	require default case in switch statements
❌	dot-location	dot-location	enforces consistent newlines before or after dots
❌	dot-notation	dot-notation	encourages use of dot notation whenever possible
☑️	eqeqeq	triple-equals	require the use of === and !==
☑️	guard-for-in	forin	make sure for-in loops have an if statement
❌	no-alert	no-alert	disallow the use of alert, confirm, and prompt
☑️	no-caller	no-arg	disallow use of arguments.caller or arguments.callee
❌	no-case-declarations	no-case-declarations	disallow lexical declarations in case clauses
❌	no-div-regex	no-div-regex	disallow division operators explicitly at beginning of regular expression
❌	no-else-return	no-else-return	disallow else after a return in an if
❌	no-empty-function	no-empty-function	disallow use of empty functions
❌	no-empty-pattern	no-empty-pattern	disallow use of empty destructuring patterns
❌	no-eq-null	no-eq-null	disallow comparisons to null without a type-checking operator
☑️	no-eval	no-eval	disallow use of eval()
❌	no-extend-native	no-extend-native	disallow adding to native types
❌	no-extra-bind	no-extra-bind	disallow unnecessary function binding
❌	no-extra-label	no-extra-label	disallow unnecessary labels
☑️	no-fallthrough	no-switch-case-fall-through	disallow fallthrough of case statements (recommended)
❌	no-floating-decimal	no-floating-decimal	disallow the use of leading or trailing decimal points in numeric literals
❌	no-implicit-coercion	no-implicit-coercion	disallow the type conversions with shorter notations
❌	no-implicit-globals	no-implicit-globals	disallow var and named functions in global scope
❌	no-implied-eval	no-implied-eval	disallow use of eval()-like methods
❌	no-invalid-this	no-invalid-this	disallow this keywords outside of classes or class-like objects
❌	no-iterator	no-iterator	disallow Usage of __iterator__ property
❌	no-labels	no-labels	disallow use of labeled statements
❌	no-lone-blocks	no-lone-blocks	disallow unnecessary nested blocks
❌	no-loop-func	no-loop-func	disallow creation of functions within loops
❌	no-magic-numbers	no-magic-numbers	disallow the use of magic numbers
✅	no-multi-spaces	no-multi-spaces	disallow use of multiple spaces
❌	no-multi-str	no-multi-str	disallow use of multiline strings
🚫	no-native-reassign	Not applicable	disallow reassignments of native objects
❌	no-new	no-new	disallow use of the new operator when not part of an assignment or comparison
❌	no-new-func	no-new-func	disallow use of new operator for Function object
❌	no-new-wrappers	no-new-wrappers	disallows creating new instances of String,Number, and Boolean
🚫	no-octal	Not applicable	disallow use of octal literals (recommended)
❌	no-octal-escape	no-octal-escape	disallow use of octal escape sequences in string literals, such as var foo = "Copyright \251";
❌	no-param-reassign	no-param-reassign	disallow reassignment of function parameters
❌	no-proto	no-proto	disallow Usage of __proto__ property
☑️	no-redeclare	no-duplicate-variable	disallow declaring the same variable more than once (http://eslint.org/docs/rules/recommended)
❌	no-return-assign	no-return-assign	disallow use of assignment in return statement
❌	no-script-url	no-script-url	disallow use of javascript: urls.
❌	no-self-assign	no-self-assign	disallow assignments where both sides are exactly the same
❌	no-self-compare	no-self-compare	disallow comparisons where both sides are exactly the same
❌	no-sequences	no-sequences	disallow use of the comma operator
❌	no-throw-literal	no-throw-literal	restrict what can be thrown as an exception
❌	no-unmodified-loop-condition	no-unmodified-loop-condition	disallow unmodified conditions of loops
☑️	no-unused-expressions	no-unused-expression	disallow Usage of expressions in statement position
❌	no-unused-labels	no-unused-labels	disallow unused labels
❌	no-useless-call	no-useless-call	disallow unnecessary .call() and .apply()
❌	no-useless-concat	no-useless-concat	disallow unnecessary concatenation of literals or template literals
❌	no-useless-escape	no-useless-escape	disallow unnecessary usage of escape character
❌	no-void	no-void	disallow use of the void operator
❌	no-warning-comments	no-warning-comments	disallow Usage of configurable warning terms in comments e.g. TODO or FIXME
❌	no-with	no-with	disallow use of the with statement
☑️	radix	radix	require use of the second argument for parseInt()
❌	vars-on-top	vars-on-top	require declaration of all vars at the top of their containing scope
❌	wrap-iife	wrap-iife	require immediate function invocation to be wrapped in parentheses
❌	yoda	yoda	require or disallow Yoda conditions

Strict Mode

These rules relate to using strict mode.

❔	ESLint	TSLint	Description
❌	strict	strict	require effective use of strict mode directives

Variables

These rules have to do with variable declarations.

❔	ESLint	TSLint	Description
❌	init-declarations	init-declarations	enforce or disallow variable initializations at definition
❌	no-catch-shadow	no-catch-shadow	disallow the catch clause parameter name being the same as a variable in the outer scope
🚫	no-delete-var	Not applicable	disallow deletion of variables (recommended)
❌	no-label-var	no-label-var	disallow labels that share a name with a variable
☑️	no-shadow	no-shadowed-variable	disallow declaration of variables already declared in the outer scope
❌	no-shadow-restricted-names	no-shadow-restricted-names	disallow shadowing of names such as arguments
🚫	no-undef	Not applicable	disallow use of undeclared variables unless mentioned in a /*global */ block (recommended)
❌	no-undef-init	no-undef-init	disallow use of undefined when initializing variables
❌	no-undefined	no-undefined	disallow use of undefined variable
☑️	no-unused-vars	no-unused-variable	disallow declaration of variables that are not used in the code (recommended)
☑️	no-use-before-define	no-use-before-define	disallow use of variables before they are defined

Node.js and CommonJS

These rules are specific to JavaScript running on Node.js or using CommonJS in the browser.

❔	ESLint	TSLint	Description
❌	callback-return	callback-return	enforce return after a callback
❌	global-require	global-require	enforce require() on top-level module scope
✅	handle-callback-err	handle-callback-err	enforce error handling in callbacks
❌	no-mixed-requires	no-mixed-requires	disallow mixing regular variable and require declarations
❌	no-new-require	no-new-require	disallow use of new operator with the require function
❌	no-path-concat	no-path-concat	disallow string concatenation with __dirname and __filename
❌	no-process-env	no-process-env	disallow use of process.env
❌	no-process-exit	no-process-exit	disallow process.exit()
❌	no-restricted-modules	no-restricted-modules	restrict Usage of specified node modules
❌	no-sync	no-sync	disallow use of synchronous methods

Stylistic Issues

These rules are purely matters of style and are quite subjective.

❔	ESLint	TSLint	Description
✅	array-bracket-spacing	array-bracket-spacing	enforce spacing inside array brackets
✅	block-spacing	block-spacing	disallow or enforce spaces inside of single line blocks
✅	brace-style	brace-style	enforce one true brace style
☑️	camelcase	variable-name	require camel case names
❌	comma-spacing	comma-spacing	enforce spacing before and after comma
❌	comma-style	comma-style	enforce one true comma style
❌	computed-property-spacing	computed-property-spacing	require or disallow padding inside computed properties
❌	consistent-this	consistent-this	enforce consistent naming when capturing the current execution context
❌	eol-last	eol-last	enforce newline at the end of file, with no multiple empty lines
❌	func-names	func-names	require function expressions to have a name
❌	func-style	func-style	enforce use of function declarations or expressions
❌	id-blacklist	id-blacklist	disallow certain identifiers to prevent them being used
❌	id-length	id-length	this option enforces minimum and maximum identifier lengths (variable names, property names etc.)
❌	id-match	id-match	require identifiers to match the provided regular expression
☑️	indent	indent	specify tab or space width for your code
❌	jsx-quotes	jsx-quotes	specify whether double or single quotes should be used in JSX attributes
❌	key-spacing	key-spacing	enforce spacing between keys and values in object literal properties
❌	keyword-spacing	keyword-spacing	enforce spacing before and after keywords
❌	linebreak-style	linebreak-style	disallow mixed 'LF' and 'CRLF' as linebreaks
❌	lines-around-comment	lines-around-comment	enforce empty lines around comments
❌	max-depth	max-depth	specify the maximum depth that blocks can be nested
❌	max-len	max-len	specify the maximum length of a line in your program
❌	max-nested-callbacks	max-nested-callbacks	specify the maximum depth callbacks can be nested
❌	max-params	max-params	specify the number of parameters that can be used in the function declaration
❌	max-statements	max-statements	specify the maximum number of statement allowed in a function
❌	max-statements-per-line	max-statements-per-line	specify the maximum number of statements allowed per line
🚫	new-cap	Not applicable	require a capital letter for constructors
❌	new-parens	new-parens	disallow the omission of parentheses when invoking a constructor with no arguments
❌	newline-after-var	newline-after-var	require or disallow an empty newline after variable declarations
❌	newline-before-return	newline-before-return	require newline before return statement
❌	newline-per-chained-call	newline-per-chained-call	enforce newline after each call when chaining the calls
❌	no-array-constructor	no-array-constructor	disallow use of the Array constructor
❌	no-continue	no-continue	disallow use of the continue statement
❌	no-inline-comments	no-inline-comments	disallow comments inline after code
❌	no-lonely-if	no-lonely-if	disallow if as the only statement in an else block
☑️	no-mixed-spaces-and-tabs	ident	disallow mixed spaces and tabs for indentation (recommended)
❌	no-multiple-empty-lines	no-multiple-empty-lines	disallow multiple empty lines
❌	no-negated-condition	no-negated-condition	disallow negated conditions
❌	no-nested-ternary	no-nested-ternary	disallow nested ternary expressions
❌	no-new-object	no-new-object	disallow the use of the Object constructor
❌	no-restricted-syntax	no-restricted-syntax	disallow use of certain syntax in code
❌	no-spaced-func	no-spaced-func	disallow space between function identifier and application
❌	no-ternary	no-ternary	disallow the use of ternary operators
☑️	no-trailing-spaces	no-trailing-whitespace	disallow trailing whitespace at the end of lines
❌	no-underscore-dangle	no-underscore-dangle	disallow dangling underscores in identifiers
❌	no-unneeded-ternary	no-unneeded-ternary	disallow the use of ternary operators when a simpler alternative exists
❌	no-whitespace-before-property	no-whitespace-before-property	disallow whitespace before properties
✅	object-curly-spacing	object-curly-spacing	require or disallow padding inside curly braces
❌	one-var	one-var	require or disallow one variable declaration per function
❌	one-var-declaration-per-line	one-var-declaration-per-line	require or disallow a newline around variable declarations
❌	operator-assignment	operator-assignment	require assignment operator shorthand where possible or prohibit it entirely
❌	operator-linebreak	operator-linebreak	enforce operators to be placed before or after line breaks
❌	padded-blocks	padded-blocks	enforce padding within blocks
❌	quote-props	quote-props	require quotes around object literal property names
❌	quotes	quote-props	specify whether backticks, double or single quotes should be used
❌	require-jsdoc	require-jsdoc	Require JSDoc comment
❌	semi	semi	require or disallow use of semicolons instead of ASI
❌	semi-spacing	semi-spacing	enforce spacing before and after semicolons
❌	sort-imports	sort-imports	enforce sorting import declarations within module
❌	sort-vars	sort-vars	sort variables within the same declaration block
❌	space-before-blocks	space-before-blocks	require or disallow a space before blocks
❌	space-before-function-paren	space-before-function-paren	require or disallow a space before function opening parenthesis
❌	space-in-parens	space-in-parens	require or disallow spaces inside parentheses
❌	space-infix-ops	space-infix-ops	require spaces around operators
❌	space-unary-ops	space-unary-ops	require or disallow spaces before/after unary operators
❌	spaced-comment	spaced-comment	require or disallow a space immediately following the // or /* in a comment
❌	wrap-regex	wrap-regex	require regex literals to be wrapped in parentheses

ECMAScript 6

These rules are only relevant to ES6 environments.

❔	ESLint	TSLint	Description
❌	arrow-body-style	arrow-body-style	require braces in arrow function body
❌	arrow-parens	arrow-parens	require parens in arrow function arguments
❌	arrow-spacing	arrow-spacing	require space before/after arrow function's arrow
❌	constructor-super	constructor-super	verify calls of super() in constructors
❌	generator-star-spacing	generator-star-spacing	enforce spacing around the * in generator functions
❌	no-class-assign	no-class-assign	disallow modifying variables of class declarations
❌	no-confusing-arrow	no-confusing-arrow	disallow arrow functions where they could be confused with comparisons
❌	no-const-assign	no-const-assign	disallow modifying variables that are declared using const
🚫	no-dupe-class-members	Not applicable	disallow duplicate name in class members
❌	no-duplicate-imports	no-duplicate-imports	disallow duplicate module imports
❌	no-new-symbol	no-new-symbol	disallow use of the new operator with the Symbol object
❌	no-restricted-imports	no-restricted-imports	restrict usage of specified modules when loaded by import declaration
❌	no-this-before-super	no-this-before-super	disallow use of this/super before calling super() in constructors.
❌	no-useless-constructor	no-useless-constructor	disallow unnecessary constructor
☑️	no-var	no-var-keyword	require let or const instead of var
❌	object-shorthand	object-shorthand	require method and property shorthand syntax for object literals
❌	prefer-arrow-callback	prefer-arrow-callback	suggest using arrow functions as callbacks
❌	prefer-const	prefer-const	suggest using const declaration for variables that are never modified after declared
❌	prefer-reflect	prefer-reflect	suggest using Reflect methods where applicable
❌	prefer-rest-params	prefer-rest-params	suggest using the rest parameters instead of arguments
❌	prefer-spread	prefer-spread	suggest using the spread operator instead of .apply().
❌	prefer-template	prefer-template	suggest using template literals instead of strings concatenation
❌	require-yield	require-yield	disallow generator functions that do not have yield
❌	template-curly-spacing	template-curly-spacing	enforce spacing around embedded expressions of template strings
❌	yield-star-spacing	yield-star-spacing	enforce spacing around the * in yield* expressions

Contributing

Bugs, rules requests, doubts etc., open a Github Issue. If you want to create a new rule or fix/improve some existing rule you can fork this repository and follow the instructions below.

• Open an issue asking for the rule or bug.
• Create a branch with the rule name, e.g: no-if-usage
• Run npm install
• Create your rule tests at ./src/test/rules and your rule in ./src/rules with the convention:
  • Name: rule-name (hyphenated, e.g: no-if-usage)
  • Rule File: ruleNameRule.ts (camelCased and with the Rule suffix, e.g: noIfUsageRule.ts)
  • Test File: ruleNameRuleTests.ts (camelCased and with the RuleTests suffix, e.g: noIfUsageRuleTests.ts)
• Check if your rule is passing with gulp test --single rule-name (hyphenated, e.g no-inner-declarations)
  • During development you may have some linting errors that won't let you run the test. You can disable the linting process with the --no-lint flag. That is run gulp test --single rule-name --no-lint
• Make sure that all the tests are passing with gulp test.
• Update the file src/readme/rules.ts with the rule information.
• To update the README file with the information you just updated run gulp readme. This will also update/create the rule documentation in docs/rules. You may add more details about the rule in this file.
• Commit the changes to your repo with the following convention:
  • Example: [feat] added use-isnan rule (closes #20)
• Finally, open a Pull Request.

You can also contribute with PRs for fixing bugs, or improving documentation, performance. The commit convention for these are, respectively:

• Example: [bug] fixed no-constant-condition rule (closes #9)
• Example: [docs] improved README.md file (closes #32)
• Example: [perf] improved valid-typeof rule (closes #48)

LICENSE

MIT