https://github.com/nicolo-ribaudo/for-own.macro

A babel-macro that makes for-in only visit own properties
https://github.com/nicolo-ribaudo/for-own.macro

Last synced: 11 days ago
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A babel-macro that makes for-in only visit own properties

• Host: GitHub
• URL: https://github.com/nicolo-ribaudo/for-own.macro
• Owner: nicolo-ribaudo
• License: mit
• Created: 2019-02-15T14:42:54.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2023-01-03T16:28:15.000Z (almost 2 years ago)
• Last Synced: 2024-10-19T18:46:29.865Z (20 days ago)
• Language: JavaScript
• Size: 293 KB
• Stars: 5
• Watchers: 3
• Forks: 1
• Open Issues: 14
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        


  
for-own.macro


  A babel-macro that makes for-in only visit own properties





## The problem

`for ... in` statements get enumerable keys from the whole prototype chain.

To prevent bugs, it is recommended to write loops like this:

```js

for (const key in obj) {

  if (obj.hasOwnProperty(key)) {

    // "key" is a property of "obj"

  }

}

```

Pretty verbose, right?

## This solution

This is a [babel-plugin-macro](https://github.com/kentcdodds/babel-plugin-macros) which allows you to iterate only over _own_ keys of an object when using `for ... in`.

## Installation

This module can be installed either with `npm` or with `yarn`, and should be installed as one of your project's `devDependencies`:

```

npm install --save-dev for-own.macro

# or

yarn add --dev for-own.macro

```

## Usage

Once you have [configured `babel-plugin-macros`](https://github.com/kentcdodds/babel-plugin-macros/blob/master/other/docs/user.md#adding-the-plugin-to-your-config) you can import/requie `import-all.macro`.

Here is an example:

```js

import own from "for-own.macro";

for (const key in own(obj)) {

  const value = obj[key];

}

//     ↓ ↓ ↓ ↓ ↓ ↓

for (const key in obj) if (Object.hasOwnProperty.call(obj, key)) {

  const value = obj[key];

}

```

## Caveats

The `own` macro only works inside `for ... in` loops. This code will throw an error at compile time:

```js

const ownProps = own(obj);

```

## LICENSE

MIT