Lint Setup

Three steps. Five minutes.

1. Install


npm install -D @ttsc/lint

ttsc and @typescript/native-preview are already in your project from the main Setup chapter. If not, install them too.

2. Register the plugin

In tsconfig.json:


{
  "compilerOptions": {
    "plugins": [{ "transform": "@ttsc/lint" }]
  }
}

That’s the entire wiring. Every ttsc build, ttsx run, and ttscserver session will now see lint diagnostics.

3. Write `lint.config.ts`

Next to tsconfig.json:


// lint.config.ts
import type { TtscLintConfig } from "@ttsc/lint";
 
export default {
  rules: {
    "no-var": "error",
    "prefer-const": "error",
    "eqeqeq": "error",
    "no-explicit-any": "warning",
 
    "format/semi": "error",
    "format/quotes": ["error", { prefer: "double" }],
    "format/trailing-comma": "error",
    "format/print-width": ["error", { printWidth: 80 }],
  },
} satisfies TtscLintConfig;

"error" fails the build. "warning" prints. "off" disables the rule.

Some rules take options as the second tuple element. Each rule’s options live on its page in Rules and Format rules.

See it


// src/index.ts
var x: number = 3;
let y: number = 4;
const z: string = 5;
 
console.log(x + y + z);


$ npx ttsc --noEmit
src/index.ts:3:7 - error TS2322: Type 'number' is not assignable to type 'string'.

3 const z: string = 5;
        ~

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

2 let y: number = 4;
      ~~~~~~~~~~~~~

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

1 var x: number = 3;
  ~~~~~~~~~~~~~~~~~~

Type errors (TS2322) and lint violations (TS17397, TS11966) come out in the same stream. Your CI step that already runs ttsc now gates lint too.

Common starter set

The config in step 3 is what most projects keep. Add and remove as you go. The full catalog is on the Rules and Format rules pages.

→ Rules — the catalog.