Putout

🐊Putout find and fix problems in your JavaScript, JSX, Typescript, Flow, Yaml, JsonandMarkdown`. It can:

• remove unused variables;
• remove unused for-of variables;
• remove unused typescripts types;
• remove unreferenced variables;
• remove unused private fields;
• remove unused expressions;
• remove useless variables;
• remove useless map;
• remove useless mapped types;
• remove useless mapping modifiers;
• remove useless continue;
• remove useless operand;
• remove useless array constructor;
• remove useless conditions;
• remove useless type conversion;
• remove useless functions;
• remove useless Array.from;
• remove useless spread;
• remove useless arguments;
• remove useless escape;
• remove useless async;
• remove useless await;
• remove useless typeof;
• remove useless template expressions;
• remove useless for-of;
• remove useless array.entries();
• remove debugger statement;
• remove iife;
• remove nested blocks;
• remove process.exit call;
• remove console.log calls;
• remove empty block statements;
• remove empty patterns;
• remove strict mode directive from esm;
• remove constant conditions;
• remove boolean from assertion;
• remove boolean from logical expressions;
• remove duplicates from logical expressions;
• remove duplicates from TypeScript Union;
• remove unreachable code;
• remove duplicate keys;
• remove useless typescripts types;
• remove duplicate typescripts interface keys;
• replace test.only to test calls;
• replace test.skip to test calls;
• reuse duplicate init;
• split variable declarations;
• split nested destructuring;
• simplify assignment;
• simplify ternary;
• simplify logical expressions;
• if absent strict mode directive in commonjs add it;
• convert apply to spread;
• convert bitwise to logical operator;
• convert concat to flat;
• convert esm to commonjs (enabled for *.cjs);
• convert commonjs to esm (enabled for *.mjs);
• convert template with one expression to string;
• convert equal to strict equal;
• convert indexOf to includes;
• convert replace to replaceAll (disabled, stage 4);
• convert assignment to arrow function;
• convert forEach to for-of;
• convert map to for-of;
• extract sequence expressions;
• extract object properties;
• add return await;
• remove useless Promise.resolve;
• convert Promise.reject to throw;
• declare undefined variables;
• apply as type assertions;
• apply utility types;
• apply array.at (not bundled);
• apply filter(Boolean);
• apply isArray;
• apply if condition;
• apply await import;

Why?

• because eslint avoids fixes that could change the runtime behavior.
• because babel produces throw-away code;
• because pretier it is a formatter;
• because jscodeshift has no config and plugins support.

The main difference of putout is saving code transformation results directly into source code in a day-to-day baisis.

Install

npm i putout -D

Usage

Usage: putout [options] [path]
Options:
   -h, --help                  display this help and exit
   -v, --version               output version information and exit
   -f, --format [formatter]    use a specific output format, the default is: 'progress-bar' localy and 'dump' on CI
   -s, --staged                add staged files when in git repository
   --fix                       apply fixes of errors to code
   --fix-count [count = 10]    count of fixes rounds
   --rulesdir                  use additional rules from directory
   --transform [replacer]      apply Replacer, for example 'var __a = __b -> const __a = __b', read about Replacer https://git.io/JqcMn
   --plugins [plugins]         a comma-separated list of plugins to use
   --enable [rule]             enable the rule and save it to '.putout.json' walking up parent directories
   --disable [rule]            disable the rule and save it to '.putout.json' walking up parent directories
   --enable-all                enable all found rules and save them to '.putout.json' walking up parent directories
   --disable-all               disable all found rules (set baseline) and save them '.putout.json' walking up parent directories
   --match [pattern]           read .putout.json and convert 'rules' to 'match' according to 'pattern'
   --flow                      enable flow
   --fresh                     generate a fresh cache
   --no-config                 avoid reading '.putout.json'
   --no-ci                     disable the CI detection
   --no-cache                  disable the cache

To find erros:

putout lib test

To fix errors:

putout lib test --fix

Plugins

By default 🐊Putout uses all enabled by default plugins, anyways it can be run with a couple mentioned plugins (splitted with ","):

putout lib --plugins remove-debugger,remove-unused-variables

Environment variables

🐊Putout supports next environment variables:

• PUTOUT_FILES - files that should be processed by putout, divided by ",";
• PUTOUT_CONFIG_FILE - path to 🐊Putout config file;
• ESLINT_CONFIG_FILE - path to ESLint config file;

PUTOUT_FILES=lib,test putout --fix

Configuration

To configure create .putout.json file and override any of default options.

Match

When you need to match paths to rules you can use match section for this purpose in .putout.json:

{
    "match": {
        "server": {
            "remove-process-exit": true
        }
    }
}

Ignore

When you need to ignore some routes no metter what, you can use ignore section in .putout.json:

{
    "ignore": [
        "test/fixture"
    ]
}

Plugins

🐊Putout supports plugins, there is two types: with prefix official @putout/plugin- and user plugins with prefix putout-plugin-. To use your plugin create plugin as npm package with keywords putout, putout-plugin and add it to .putout.json.

For example if you need to remove-something create 🐊Putout plugin with name putout-plugin-remove-something and it to package.json:

{
    "plugins": [
        "remove-something"
    ]
}

Codemods

🐊Putout supports codemodes in the similar to plugins way, just create a directory ~/.putout and put your plugins there. Here is example: convert-tape-to-supertape and this is example of work.

API

putout(source, options)

const putout = require('putout');

const source = `
const t = 'hello';
const m = t + '!';
console.log(t);
`;

putout(source, {
    plugins: [
        'remove-unused-variables',
    ],
});
// returns
`
const t = 'hello';
console.log(t);
`;

License

MIT