v5.0.0

NPM distribution note: tslint@next is deprecated now that the standard tslint package allows a peer dependency of typescript@next. Please switch to tslint@latest.

🔥 Breaking changes

• Minimum version of TypeScript is now 2.1.0 (#2425)
• The severity level of each rule is now configurable and defaults to severity "error". This affects the output of formatters:
  • [formatter] msbuild was outputting all failures as "warning".
  • [formatter] pmd was outputting all failures as priority 1. Now, it uses priority 3 for "error" (default) and priority 4 for "warning"
• [formatter] json changed the fix property to now contain either one replacement or an array of replacements (#2403)
• tslint:recommended configuration updated with tslint:latest rules & options (#2424)
• Removed no-unused-new rule, with logic moved into no-unused-expression (#2269)
• no-trailing-whitespace now checks template strings by default. Use the new options ignore-template-strings to restore the old behavior. (#2359)
• Some rules that previously worked without the type checker now require it. This includes:
  • no-unused-variable
  • no-use-before-declare

API breaks for editor integration

• LintResult.failureCount is now separated into LintResult.errorCount and LintResult.warningCount
• class Fix is now type Fix = Replacement | Replacement[]

API breaks for custom rules

• Removed method skip from RuleWalker (#2313)

• Removed all use of the TypeScript Language Service, use only Program APIs instead (#2235)

  • This breaks custom rule compilation. If your rule was not using the ts.LanguageService APIs, the migration is quite simple:

  - public applyWithProgram(srcFile: ts.SourceFile, langSvc: ts.LanguageService): Lint.RuleFailure[] {
  -     return this.applyWithWalker(new Walker(srcFile, this.getOptions(), langSvc.getProgram()));
  + public applyWithProgram(srcFile: ts.SourceFile, program: ts.Program): Lint.RuleFailure[] {
  +     return this.applyWithWalker(new Walker(srcFile, this.getOptions(), program));

  • N.B. If you are refactoring your custom rules, consider these performance tips for writing custom rules.

• Removed createFix. Replacements should be passed directly into addFailure. (#2403)

• Removed deprecated scanAllTokens and skippableTokenAwareRuleWalker (#2370)

🎉 Notable features & enhancements

• [feature] The severity level of each rule is now individually configurable. Default severity can also be configured for a config file. (#629, #345)

  • Valid values for severity: default | error | warn | warning | none | off
  • Valid values for defaultSeverity: error | warn | warning | none | off
  • Old style:

  {
      "extends": "tslint:latest",
      "rules": {
          "callable-types": true,
          "max-line-length": [true, 140]
      }
  }

  • New style (in this example, callable-types outputs errors and max-line-length outputs warnings):

  {
      "extends": "tslint:latest",
      "defaultSeverity": "error",
      "rules": {
          "callable-types": true,
          "max-line-length": {
              "options": 140,
              "severity": "warning"
          }
      }
  }

• [new-rule] prefer-template (#2243)

• [new-rule] return-undefined (#2251)

• [new-rule] no-reference-import (#2273)

• [new-rule] no-unnecessary-callback-wrapper (#2249)

• [new-fixer] linebreak-style (#2394)

• [new-fixer] eofline (#2393)

Full list of changes

• [api] Added class OptionallyTypedRule, which allows rule authors to write a rule that applies when typing is either enabled or disabled (#2300)
• [bugfix] prefer-function-over-method now ignores abstract methods (#2307)
• [bugfix] arrow-parens with option ban-single-arg-parens now correctly handles functions with return type annotation (#2265)
• [bugfix] prefer-function-over-method exclude overload signatures (#2315)
• [bugfix] use-isnan now applies only to comparison operators (#2317)
• [bugfix] file-header-rule now handles single-line comments correctly (#2320)
• [bugfix] newline-before-return: fix handling of blank lines between comments (#2321)
• [bugfix] trailing-comma No longer enforce trailing commas in type parameters and tuple types (#2236)
• [bugfix] align don't fix if it would remove code (#2379)
• [bugfix] unified-signatures now recognizes rest parameters (#2342)
• [bugfix] no-inferrable-types don't warn for inferrable type on readonly property (#2312)
• [bugfix] trailing-comma no longer crashes on new without parentheses (e.g. new Foo) (#2389)
• [bugfix] semicolon Ignore comments when checking for unnecessary semicolon (#2240)
• [bugfix] semicolon Don't report unnecessary semicolon when followed by regex literal (#2240)
• [bugfix] CLI: exit with 0 on type check errors when --force is specified (#2322)
• [bugfix] CLI: --test now correctly strips single quotes from patterns on windows (#2322)
• [bugfix] prefer-const only fix initialized variables (#2219)
• [bugfix] prefer-const correctly handle variables shadowed by parameters and catched exceptions (#2219)
• [bugfix] prefer-const don't warn if one variable in a for loop initializer can not be const (#2219)
• [bugfix] prefer-const handle more cases in destructuring (#2219)
• [bugfix] no-unused-expression allow comma separated assignments (#2269)
• [chore] removed update-notifier dependency (#2262)
• [development] allow rule tests to specify version requirement for typescript (#2323)
• [enhancement] ignore-properties option of no-inferrable-types now also ignores parameter properties (#2312)
• [enhancement] unified-signatures now displays line number of the overload to unify if there are more than 2 overloads (#2270)
• [enhancement] trailing-comma New checks for CallSignature and NamedExports (#2236)
• [enhancement] semicolon New check for export statements, function overloads and shorthand module declaration (#2240)
• [enhancement] semicolon Report unnecessary semicolons in classes and in statement position (for option "always" too) (#2240)
• [enhancement] semicolon check for semicolon after method overload (#2240)
• [enhancement] array-type now consider object, undefined and never as simple types, allowing object, undefined[] and never[] (#1843)(#2353)
• [enhancement] align check statement alignment for all blocks (#2379)
• [enhancement] aligncheck parameter alignment for all signatures (#2379)
• [enhancement] --test can handle multiple paths at once (#2322)
• [enhancement] only-arrow-functions allow functions that use this in the body (#2229)
• [enhancement] CLI: print error when --type-check is used without --project (#2322)
• [enhancement] CLI: don't print stack trace on type check error (#2322)
• [enhancement] CLI: added -p as shorthand for --project to be consistent with tsc (#2322)
• [enhancement] prefer-const show warnings for var (#2219)
• [enhancement] quotemark fixer unescapes original quotemark (e.g. '\'' -> "'") (#2359)
• [enhancement] no-unused-expression allow indirect eval (0, eval)(""); (#2269)
• [enhancement] no-unused-expression checking for unused new can now use option allow-fast-null-checks (#2269)
• [enhancement] no-unused-expression find unused comma separated expressions in all locations of the code (#2269)
• [enhancement] no-unused-expression find unused expressions inside void expression (#2269)
• [new-config-option] Adds defaultSeverity with options error, warning, and off. (#2416)
• [new-formatter] TAP formatter (#2325)
• [new-rule-option] no-unused-expression adds option allow-tagged-template to allow tagged templates for side effects (#2269)
• [new-rule-option] no-unused-expression adds option allow-new to allow new without using the new object (#2269)
• [new-rule-option] member-access adds no-public option (#2247)
• [new-rule-option] curly added option ignore-same-line (#2334)
• [new-rule-option] {destructuring: "all"} to only warn if all variables in a destructuring can be const (#2219)
• [new-rule-option] added ignore-template-strings to no-trailing-whitespace (#2359)
• [rule-update] array-type now consider undefined and never as simple types, allowing undefined[] and never[] (#1843)

Thanks to our contributors!

• Brian Olore
• Andy Hanson
• @andy-ms
• Chris Barr
• Klaus Meinhardt
• @bumbleblym
• Josh Goldberg
• James Clark
• @vilic
• Aleksandr Filatov
• Matt Banz
• Karol Janyst
• Mike Deverell
• Alexander James Phillips
• Irfan Hudda