https://github.com/noahsug/gen-codemod

Generate codemods by specifying your starting -> desired JavaScript.
https://github.com/noahsug/gen-codemod

Last synced: 3 months ago
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Generate codemods by specifying your starting -> desired JavaScript.

• Host: GitHub
• URL: https://github.com/noahsug/gen-codemod
• Owner: noahsug
• Created: 2018-02-12T22:37:20.000Z (about 7 years ago)
• Default Branch: master
• Last Pushed: 2018-02-28T01:36:05.000Z (almost 7 years ago)
• Last Synced: 2024-11-02T21:31:46.489Z (3 months ago)
• Language: JavaScript
• Size: 613 KB
• Stars: 21
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

• awesome-codemods - gen-codemod - Generate codemods by specifying your starting -> desired JavaScript. (Misc / ant-design)

README

        
# gen-codemod

> Generate codemod by comparing two JavaScript files.

Demo: [Codemod Explorer](https://noahsug.github.io/gen-codemod/)

### Usage

`gen-codemod INITIAL.js DESIRED.js > my-transform.js`

`INITIAL.js` is the initial, pre-codemod JavaScript you'd like to change.

`DESIRED.js` is the desired, post-codemod JavaScript you'd like to have.

`gen-codemod` compares these two files and creates a codemod to get from `INITIAL.js` to `DESIRED.js`.

### Example

When upgrading from sinon.js v1 -> v2, every instance of `sinon.stub(obj, method, fn)` needs to be changed to `sinon.stub(obj, method).andCallsFake(fn)`. We can generate this codemod as follows:

```sh

echo "sinon.stub(A, B, C)" > sinon-v1.js

echo "sinon.stub(A, B).andCallFake(C)" > sinon-v2.js

gen-codemod sinon-v1.js sinon-v2.js

```

**Note:** Single uppercase letters, such as `A`, `B`, `C`, etc, are used as variables and match any AST node.

This outputs:

```js

module.exports = function(file, api) {

  const j = api.jscodeshift;

  const rootProperties = {

    type: 'CallExpression',

    callee: {

      type: 'MemberExpression',

      object: { type: 'Identifier', name: 'sinon' },

      property: { type: 'Identifier', name: 'stub' },

      computed: false

    },

    arguments: [{}, {}, {}]

  };

  function getTransform(path) {

    return j.callExpression(

      j.memberExpression(

        j.callExpression(

          j.memberExpression(

            j.identifier('sinon'),

            j.identifier('stub'),

            false

          ),

          [getANode(path), getBNode(path)]

        ),

        j.identifier('andCallsFake'),

        false

      ),

      [getCNode(path)]

    );

  }

  function getANode(path) {

    return path.node.arguments[0];

  }

  function getBNode(path) {

    return path.node.arguments[1];

  }

  function getCNode(path) {

    return path.node.arguments[2];

  }

  return j(file.source)

    .find(j.CallExpression, rootProperties)

    .replaceWith(getTransform)

    .toSource();

};

```

To run your codemod, use [jscodeshift](https://github.com/facebook/jscodeshift):

```sh

gen-codemod sinon-v1.js sinon-v2.js > my-transform.js

npx jscodeshift -t my-transform.js PROJECT_PATH

```

### Install

`npm i -g gen-codemod`

### Limitations

Can't change multiple AST expressions at once (only reads the first AST node from the initial / desired JavaScript files).