TSLint 4.0 Released

TSLint 4.0 has been released! With this release comes a few exciting changes. Some of the highlights:

• Fixers. Do you dread turning on a new rule because of all of the new errors? For some of the most common issues, we’ll fix them for you. To use this feature, run tslint with the --fix option. Rules that support the --fix feature:
  • array-type
  • arrow-parens
  • no-unused-variable (for imports)
  • no-var-keyword
  • ordered-imports
  • semicolon
  • trailing-comma

• Linting .js files. A much-requested feature from our community. Simplify your toolset by running the same rules you know and love on your .js and .jsx files. Just add a jsRules section to your tslint.json file, and TSLint will lint your JavaScript files.

• TypeScript 2.0+ required. This lets us deprecate/remove rules that are checked by the compiler. Problematic code that once violated these rules now cause compilation errors in tsc:
  • no-duplicate-key
  • no-unreachable
  • no-unused-variable

• Node.js API Change. Moved and renamed some things to make more sense. Get it all when you use import * as TSLint from "tslint".

• Recommended Rules Updated
  • adjacent-overload-signatures
  • array-type
  • arrow-parens
  • max-classes-per-file
  • no-unsafe-finally
  • object-literal-key-quotes (as needed)
  • object-literal-shorthand
  • only-arrow-functions
  • ordered-imports
  • prefer-for-of
• Other rules you might find handy:
  • completed-docs
  • cyclomatic-complexity

Create your own fixer

To create your own fixer, instantiate a Fix object and pass it in as an argument to addFailure.

This snippet updates the sample custom rule by adding a fixer which replaces the offending import statement with an empty string:

// create a fixer for this failure
const replacement = new Lint.Replacement(node.getStart(), node.getWidth(), "");
const fix = new Lint.Fix("no-imports", [replacement]);

this.addFailure(this.createFailure(node.getStart(), node.getWidth(), Rule.FAILURE_STRING, fix));