jsfmt

For formatting, searching, and rewriting JavaScript. Analogous to gofmt.

Installation

npm install -g jsfmt

Usage

$ jsfmt --help
Usage:
  jsfmt [--no-format] [--save-ast] [--diff, --list, --write] [--validate] [--rewrite PATTERN, --search PATTERN] [--json, --ast] [<file>...]
  jsfmt (--version, --help)

Options:
  -h --help                      Show this help text
  --version                      Show jsfmt version
  -d --diff                      Show diff against original file
  -l --list                      List the files which differ from jsfmt output
  -v --validate                  Validate the input file(s)
  --no-format                    Do not format the input file(s)
  -w --write                     Overwrite the original file with jsfmt output
  -j --json                      Tell jsfmt that the file being parsed is json
  -a --ast                       Tell jsfmt that the file being parsed is in JSON AST
  --save-ast                     Output the resulting js in JSON AST format
  -r=PATTERN --rewrite PATTERN   Rewrite rule (e.g., 'a.slice(b, len(a) -> a.slice(b)')
  -s=PATTERN --search PATTERN    Search rule (e.g., 'a.slice')

If no path is given it will read from stdin. A directory path will recurse over all *.js files in the directory.

Note that the AST options (--ast and --save-ast) are experimental and may be removed.

Formatting

For formatting jsfmt uses esformatter.

.jsfmtrc

Any of the esformatter formatting
options can be overwritten via a .jsfmtrc file. The file is parsed using
rc, which accepts either a json or ini formatted file.

A .jsfmtrc will be read if it exists in any of the following directories:

• a local .jsfmtrc or the first found looking in ./ ../ ../../ ../../../ etc.
• $HOME/.jsfmtrc
• $HOME/.jsfmt/config
• $HOME/.config/jsfmt
• $HOME/.config/jsfmt/config
• /etc/jsfmtrc
• /etc/jsfmt/config

jsfmt will also attempt to pickup and use the configured indent
variable from your .jshintrc configuration file, if present.

Rewriting

The --rewrite flag allows rewriting portions of the JavaScript's AST before formatting. This is especially handy for intelligent renaming and handling API changes from a library. The rewrite rule must be a string of the form:

pattern -> replacement

Both pattern and replacement must be valid JavaScript. In pattern, single-character lowercase identifiers serve as wildcards matching arbitrary expressions; those expressions will be substituted for the same identifiers in the replacement.

Example

Rewrite occurences of _.reduce to use native reduce:

jsfmt --rewrite "_.reduce(a, b, c) -> a.reduce(b, c)" reduce.js

Searching

The --search flag allows searching through a JavaScript's AST. The search rule is very similar to the rewrite rule but just outputs expressions that match the given search expression. The search expression must be valid JavaScript.

Example

Find occurences of _.reduce:

jsfmt --search "_.reduce(a, b, c)" reduce.js

Validating

The --validate flag will print any errors found by esprima while parsing the JavaScript.

Example

jsfmt --validate bad.js

API

Formatting

jsfmt.format(<javascript_string>, <config_object>) // Returns formatted JavaScript

jsfmt.formatJSON(<JSON_string>, <config_object>) // Returns formatted JSON

var config = jsfmt.getConfig(); // Loads the jsfmt config from the appropriate rc file or default config object

Example

var jsfmt = require('jsfmt');
var fs = require('fs');

var js = fs.readFileSync('unformatted.js');
var config = jsfmt.getConfig();

js = jsfmt.format(js, config);

Rewriting

jsfmt.rewrite(<javascript_string>, <rewrite_rule>) // Returns rewritten JavaScript

Example

var jsfmt = require('jsfmt');
var fs = require('fs');

var js = fs.readFileSync('each.js');

js = jsfmt.rewrite(js, "_.each(a, b) -> a.forEach(b)");

Searching

jsfmt.search(<javascript_string>, <search_expression>) // Returns array of matches

Example

var jsfmt = require('jsfmt');
var fs = require('fs');

var js = fs.readFileSync('component.js');

jsfmt.search(js, "R.Component.create(a, { dependencies: z })").forEach(function(matches, wildcards) {
  console.log(wildcards.z);
});

Validating

jsfmt.validate(<javascript_string>) // Returns errors found while parsing JavaScript

jsfmt.validateJSON(<JSON_string>) // Returns errors found while parsing JSON

Example

var jsfmt = require('jsfmt');
var fs = require('fs');

var js = fs.readFileSync('each.js');
var errors = jsfmt.validate(js);

for (var i = 0; i < errors.length; i++) {
  console.error(errors[i]);
}

Plugins

Since jsfmt uses esformatter under the covers for formatting your code you can utilize any esformatter plugins with jsfmt. Please see https://github.com/millermedeiros/esformatter/#plugins for more information.

JSX

There exists a plugin esformatter-jsx which provides support for formatting JSX with esformatter. Please see https://github.com/royriojas/esformatter-jsx/wiki/Usage-with-jsfmt for more information on setting up with jsfmt.

Links

• vim-jsfmt.vim - https://github.com/mephux/vim-jsfmt - "Format javascript source on save."
• Atom Package - https://atom.io/packages/atom-jsfmt - "Automatically run jsfmt every time you save a JavaScript source file."
• Grunt Task - https://github.com/james2doyle/grunt-jsfmt - "A task for the jsfmt library."
• Emacs Plugin - https://github.com/brettlangdon/jsfmt.el - "Run jsfmt from within emacs"
• Gulp Task - https://github.com/blai/gulp-jsfmt - "A gulp task for jsfmt."
• Sublime Text plugin - https://github.com/ionutvmi/sublime-jsfmt - "On-demand and automatic jsfmt from Sublime Text 2 and 3"

Changelog

v0.4.0

• Added two new command-line args for AST formatting. Note that these are experimental and may be removed.
• Removed --config option in favor of .jsfmtrc and better docs around rc.
• Updated esformatter and using new esformatter plugin for automatic brace insertion.
• Updated style guide to include esformatter changes.
• Fixes and cleanup for shebang.
• Support for variable arguments using ES6 rest syntax.
• General rewrite cleanup.
• Changing exit code to -1 on missing arg failure.
• Updates to rc and other dependencies.

v0.3.2

• Adding support for UnaryExpression
• Fixing bug where rewrite types were not being set properly

v0.3.1

• Fixed bug when searching for expressions within BlockStatement or Program body
• Added JSON support

v0.3.0

• Added CONTRIBUTING
• Added tests
• Added Gruntfile for development
• Added CI support
• Added style guide
• Added default formatting config
• Exposed jsfmt.getConfig api method for loading jsfmt config
• Exposed jsfmt.format(js[, options]) api method for formatting
• Added --validate option and exposed jsfmt.validate api method
• Pinned dependencies

v0.2.0

• Add rc and --config config.json support for formatting configuration
• Making --format the default action
• Fix support for shebang at the top of js files, e.g. #!/usr/bin/env node
• Fix jsfmt diff mode where whitespace was unaccounted for due to -b git diff option

v0.1.1

• Initial release

License

Apache License, Version 2.0. Copyright 2014 Rdio, Inc.