What is TypeScript Formatter?

A TypeScript formatter is a tool that parses TypeScript source code and re-emits it with Prettier-standard spacing, line breaks, quote style, and semicolons so every file in a codebase follows the same visual conventions. The compiled JavaScript never changes, only the source representation does.

Frontend and full-stack engineers reach for a TypeScript formatter when a snippet from Stack Overflow, an AI assistant, or a stale tutorial needs to match the surrounding project style before paste.

Why use a TypeScript formatter?

Match Prettier defaults without a local install. When you pull a snippet from outside the project, formatting it once in the browser saves a round trip through prettier --write and a package.json install.
Normalize quote style and semicolons. Mixed single and double quotes plus optional trailing semicolons produce noisy diffs. Reformatting picks one convention and applies it uniformly.
Detect parse errors before commit. A malformed generic, a missing >, or an unbalanced template literal fails formatting with a precise line and column reference.
Standardize type annotation spacing. Spaces around :, =, and => look subtly different across editors. A formatter eliminates the drift.

How to use the TypeScript Formatter

Paste your TypeScript code into the Input panel. JSX and TSX syntax is supported.
Click Format. The code is parsed with the TypeScript AST and re-emitted using Prettier defaults.
Read the rewritten code in the Output panel. Parse errors appear above the input area with a line reference.
Click Copy to copy the formatted code to your clipboard, then paste it back into your editor.

TypeScript formatting rules

The formatter applies the defaults shipped by Prettier for the TypeScript parser. These match the conventions used in roughly 80% of open-source TypeScript projects on GitHub.

Option	Default	Notes
`printWidth`	80	Wraps long lines at column 80
`tabWidth`	2	Two-space indentation
`useTabs`	false	Spaces, not tabs
`semi`	true	Trailing semicolons on statements
`singleQuote`	false	Double quotes for strings, single inside JSX attributes
`trailingComma`	”all”	Trailing commas in multi-line objects, arrays, and parameter lists
`bracketSpacing`	true	Spaces inside object literals: `{ a: 1 }`
`arrowParens`	”always”	`(x) => x` not `x => x`

Examples

A snippet with mixed quotes, missing semicolons, and inconsistent spacing:


type User = {id:number,email:string, createdAt :Date}
const find = async (id:number):Promise<User|null>=>{
const res = await fetch(`/api/users/${id}`)
if(!res.ok)return null
return res.json()}

After formatting, spacing, quotes, and semicolons are uniform:


type User = { id: number; email: string; createdAt: Date };
const find = async (id: number): Promise<User | null> => {
  const res = await fetch(`/api/users/${id}`);
  if (!res.ok) return null;
  return res.json();
};

Common use cases

Frontend developers cleaning up snippets pasted from chat, blog posts, or AI assistants before merging them into a React or Next.js codebase.
Code reviewers reformatting a contributor’s pull request locally to separate style noise from logic changes.
Bootcamp learners matching the Prettier conventions used by the project they are studying.
Technical writers producing TypeScript code samples for documentation that needs to stay style-consistent across pages.

Frequently asked questions

Does this TypeScript formatter run my code?

No. The formatter parses the code into an abstract syntax tree, rewrites it, and prints it back out. It never evaluates the program, fetches a URL, or accesses anything outside the input text.

Does it support TSX and JSX?

Yes. JSX expressions inside TypeScript files are parsed and formatted with the same conventions: JSX attribute strings use single quotes, multi-line JSX children indent two spaces, and self-closing tags include a space before />.

How is this different from running Prettier locally?

The output matches prettier --parser typescript with default options. The browser version skips the install step. For save-on-format across a repo, install Prettier in the project.

Will it preserve my comments?

Yes. Line and block comments stay in their original position. JSDoc blocks above functions and types keep their indentation.

Can it format `.d.ts` files?

Yes. Declaration files use the same parser. Ambient module declarations, namespace blocks, and conditional types format with the same rules as regular .ts source.

Does it organize imports?

No. Import sorting is outside Prettier’s scope. Use @trivago/prettier-plugin-sort-imports or the ESLint rule simple-import-sort instead.

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