What does trailingComma: "all" actually do?

It adds a trailing comma after the last element in multi-line arrays, objects, and function parameters/arguments wherever the target syntax supports it (this has been valid in all modern JS/TS runtimes for years). "es5" only adds them where ES5 already allowed trailing commas (arrays/objects, not function parameters), and "none" never adds them.

Why generate a .prettierignore alongside .prettierrc?

Without a .prettierignore, Prettier will try to format everything, including build output, lockfiles, and minified files, which is slow and can corrupt generated files that aren't meant to be reformatted. The generated ignore file excludes the common offenders (node_modules, dist, build, lockfiles, minified JS) as a sensible starting point.

Should semi and singleQuote match my ESLint config?

They should match whatever your team has agreed on, but more importantly, if you're also running ESLint's stylistic rules, they need to agree with these settings or the two tools will fight over the same lines. Most teams disable ESLint's formatting-related rules entirely and let Prettier own formatting.

Does Prettier configuration support more options than this tool exposes?

Yes, Prettier has additional options (bracketSpacing, arrowParens, endOfLine, and language-specific overrides); this tool covers the handful of settings most teams actually customize, and you can hand-edit the generated file to add more.

Prettier Config Generator - .prettierrc + .prettierignore

Overview

Introduction

Prettier's whole pitch is that formatting stops being a discussion, but that only works once a team agrees on the handful of options it does expose, print width, tab width, semicolons, quote style, and trailing commas, and writes them down in a shared .prettierrc.

This tool generates that .prettierrc as valid JSON, plus a matching .prettierignore covering the paths Prettier shouldn't touch, from a simple options form.

What Is Prettier Config Generator?

A .prettierrc and .prettierignore generator covering Prettier's most commonly customized settings: printWidth, tabWidth, semi, singleQuote, and trailingComma.

The .prettierignore output is pre-populated with the standard exclusions almost every project needs: node_modules, build output directories, lockfiles, and minified files.

How Prettier Config Generator Works

Print width and tab width are validated as sensible integers (20-200 and 1-8 respectively) before being written into the config object alongside the boolean/enum settings.

The whole options object is serialized with JSON.stringify(config, null, 2), producing the same 2-space-indented JSON shape Prettier's own `--config` examples use.

When To Use Prettier Config Generator

Use it when adding Prettier to a project for the first time and you want a valid, team-agreed .prettierrc without hand-writing the JSON.

It's also useful for quickly producing a .prettierignore for a project that has Prettier installed but no ignore file yet, avoiding accidental reformatting of build output or lockfiles.

Often used alongside ESLint Flat Config Generator and package.json Generator.

Features

Advantages

Validates printWidth/tabWidth ranges so the generated config can't contain a nonsensical value like printWidth: 0.
Bundles a sensible .prettierignore alongside the config, covering the exclusions almost every project needs on day one.
Output is exactly the JSON shape Prettier expects for .prettierrc, ready to save with no further editing.

Limitations

Only covers the five most commonly customized options; less frequently changed settings (bracketSpacing, arrowParens, endOfLine) aren't exposed and default to Prettier's own defaults if omitted.
Doesn't detect or resolve conflicts with an existing ESLint stylistic-rules configuration; that's a separate, manual coordination step.

Examples

A compact single-quote, no-semicolon style

Input

printWidth: 100, tabWidth: 2, semi: false, singleQuote: true, trailingComma: all

Output

{
  "printWidth": 100,
  "tabWidth": 2,
  "semi": false,
  "singleQuote": true,
  "trailingComma": "all"
}

Best Practices & Notes

Best Practices

Commit .prettierrc and .prettierignore to the repository so every contributor's editor and CI format the same way, rather than relying on individual editor defaults.
Disable ESLint's own formatting-related stylistic rules once Prettier is in place, so the two tools don't disagree over the same line.
Run Prettier in CI (`prettier --check`) in addition to editor integrations, so unformatted code fails the build instead of only showing a squiggly underline locally.

Developer Notes

trailingComma defaults to Prettier's modern default of "all" in most current examples, since every JS/TS runtime Prettier targets today accepts trailing commas after the last function argument; "es5" remains available for teams whose toolchain still needs ES5-only trailing-comma placement. The .prettierignore list intentionally mirrors common .gitignore entries (node_modules, dist, build, out, coverage) plus lockfiles, since reformatting a lockfile can produce large, meaningless diffs.

Prettier Config Generator Use Cases

Adding Prettier to a project for the first time with an agreed-on formatting style
Standardizing .prettierrc settings across multiple repositories on a team
Generating a .prettierignore for a project that has Prettier but no ignore file yet

Common Mistakes

Running Prettier without a .prettierignore and having it reformat a committed lockfile or minified vendor file, producing a huge unreviewable diff.
Leaving ESLint stylistic rules enabled alongside Prettier with conflicting settings, causing the two tools to repeatedly fight over the same lines on save.

Tips

Use the ESLint Config Generator next and make sure any stylistic rules it might enable are turned off or delegated to Prettier.

Prettier Config Generator