Configuration file

Where tidy looks for tidy.json, how the nearest one wins, and how it stacks with .editorconfig and the command line.

tidy reads one config file per file it formats: the nearest one above it. There is no extends, no cascade of several configs, and no plugin resolution.

File names

In each folder, tidy looks for these, in this order, and uses the first it finds:

tidy.json
tidy.jsonc
tidy.toml

tidy.json is parsed as JSONC, so comments and trailing commas are fine in it too. The .jsonc name exists only to say so.

tidy.json

{
  "width": 100,
  "js": { "semi": false, "quote": "single" },
  "markdown": { "wrap": "always" }
}

tidy.toml

width = 100

[js]
semi = false
quote = "single"

[markdown]
wrap = "always"

The two are the same config. Keys are identical; TOML tables are the language sections.

Which config a file gets

For each file, tidy walks up from the file's own folder and uses the first config it finds. It stops at the root of the filesystem.

repo/
  tidy.json            ← used by everything below, except
  src/
    app.ts
  vendor/
    tidy.json          ← used by everything in vendor/
    legacy.js

Configs do not merge. vendor/legacy.js takes vendor/tidy.json and nothing from repo/tidy.json. If you want shared values, repeat them.

Shared keys and language sections

A key at the top level applies to every language that has it. A key inside a language section applies to that language only, and wins:

tidy.json

{
  "width": 100,
  "quote": "single",
  "markdown": { "width": 80 }
}

Everything is formatted at 100 columns with single quotes; Markdown is wrapped against 80.

The sections are html, vue, handlebars, css, json, yaml, toml, xml, markdown, dockerfile, ini, graphql and js. css covers SCSS and Less; json covers JSONC and JSON5; js covers TypeScript and JSX. See Options for what each accepts.

What wins

From weakest to strongest:

tidy's defaults, which are Prettier's.
.editorconfig, for the properties it maps. See EditorConfig.
The nearest tidy.json, tidy.jsonc or tidy.toml — first its shared keys, then its language section.
Options given on the command line.

Shell

# the config says 100; this run uses 120
$ tidy up . --width 120

Overriding the search

Flag	What it does
`--config <path>`	Use this file for every file, wherever they are. `.editorconfig` still applies.
`--no-config`	Read no config files, and no `.editorconfig`. Defaults and command-line flags only.

--no-config is the way to see what tidy does with nothing set, which is what the comparisons on this site use.

Errors

A config that does not parse, or that sets a key tidy does not know, stops the run with exit code 2 and a message that names the key:

tidy: tidy.json: unknown option `js.printWidth`

That is deliberate: a typo in a config is a silent change in output otherwise. The option you want there is width, under js or at the top level — see Options for the mapping from Prettier's names.