Lint & Format

@ttsc/lint folds ESLint’s job and Prettier’s job into the compile you already run. No plugin resolution ceremony, no formatter fighting the linter: one config file, one pass, one exit code.

Install

npm install -D ttsc @ttsc/lint typescript

pnpm add -D ttsc @ttsc/lint typescript

yarn add -D ttsc @ttsc/lint typescript

bun add -d ttsc @ttsc/lint typescript

The config file

Drop a lint.config.ts next to tsconfig.json:

// lint.config.ts
import type { ITtscLintConfig } from "@ttsc/lint";
 
export default {
  rules: {
    "no-var": "error",
    "prefer-const": "error",
    "eqeqeq": "error",
    "typescript/no-explicit-any": "warning",
  },
  format: {
    printWidth: 100,
    singleQuote: true,
    trailingComma: "all",
  },
} satisfies ITtscLintConfig;

Three severities: "error" fails the build, "warning" prints, "off" disables. Rules with options take an ESLint-style tuple, ["error", { "allowElseIf": false }].

The format block configures the formatter and its keys mirror .prettierrc. Its mere presence (even an empty format: {}) enables ttsc format at Prettier defaults; it does not fail the build on formatting unless you set format.severity.

See it fail

// src/index.ts
var count = 3;
let total = count;

$ npx ttsc --noEmit
src/index.ts:2:5 - error TS17397: [prefer-const] Use const instead of let.

2 let total = count;
      ~~~~~~~~~~~~~

src/index.ts:1:1 - error TS11966: [no-var] Unexpected var, use let or const instead.

1 var count = 3;
  ~~~~~~~~~~~~~~

Lint violations arrive as compiler diagnostics, in the same stream as type errors, with the rule name in brackets. The CI step that already runs ttsc --noEmit now gates lint too, for free.

Cleaning up

npx ttsc fix      # apply every fixable lint violation + format edits, then re-check
npx ttsc format   # format edits only, never changes behavior

In the editor, the VS Code extension surfaces the same diagnostics live and formats on save with this same format block.

Next

• Lint Setup: ignores, configFile, config discovery, and caching.
• Format: every format key and the rules it drives.
• Rules: the full rule catalog.