prettier-transform

Install

yarn add --dev prettier-transform

Usage with prettier

Add to your prettier configuration file (.prettierrc):

{
  "transform": {
    "parser": "babylon",
    "transforms": [
      "./my-transform"
    ]
  }
}

Then invoke prettier using the parser API:

prettier --parser ./node_modules/prettier-transform --write "**/*.js"

If you want to do different transforms for different files, you can make use of prettier's overrides configuration:

{
  "overrides": [
    {
      "files": "*.jsx",
      "options": {
        "transform": {
          "parser": "babylon",
          "transforms": ["./transform-a", "./transform-b"]
        }
      }
    }
  ]
}

Writing Transforms

Transforms must be standard JavaScript modules that export a function that takes an AST and returns an AST.

If you're working with a babylon-produced AST, you can do the following:

const traverse = require("babel-traverse").default;
 
module.exports = ast => {
  traverse(ast, {
    Identifier(path) {
      if (path.node.name === "foo") {
        path.node.name = "bar";
      }
    }
  });
  return ast;
};

API Usage

Basic usage:

const prettierTransform = require("prettier-transform");
const myTransform = require("./my-transform");
 
prettierTransform.format("foo()", [myTransform], { parser: "babylon" });

Pass options to prettier:

prettierTransform.format("foo()", [myTransform], {
  parser: "babylon",
  semi: false
});