@putout/plugin-spread [![NPM version][NPMIMGURL]][NPMURL]

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[NPMURL]: https://npmjs.org/package/@putout/plugin-spread "npm"

> Spread syntax can be used when all elements from an object or array need to be included in a list of some kind.
>
> (c) MDN

🐊Putout plugin adds ability to transform spread syntax.

Install

``
npm i @putout/plugin-spread
`

Rules

- ✅ convert-apply-to-spread;
- ✅ convert-convert-object-assign-to-merge-spread;
- ✅ simplify-nested;
- ✅ remove-useless-array;
- ✅ remove-useless-object;

Rule

`json
{
"rules": {
"spread/convert-apply-to-spread": "on",
"spread/convert-object-assign-to-merge-spread": "on",
"spread/remove-useless-array": "on",
"spread/remove-useless-object": "on",
"spread/simplify-nested": "on"
}
}
`

convert-object-assign-to-merge-spread

> The Object.assign() method copies all enumerable own properties from one or more source objects to a target object and returns the modified target object.
>
> Spread syntax (...) allows an object expression to be expanded in places where zero or more key-value pairs are expected.
>
> (c) MDN

Convert Object.assign() to merge spread since it shorter but does (mostly) the same.

$3

`js
function merge(a) {
return Object.assign({}, a, {
hello: 'world',
});
}
`

$3

`js
function merge(a) {
return {
...a,
hello: 'world',
};
}
`

$3

Linter | Rule | Fix
--------|-------|------------|
🐊 Putout | spread/convert-object-assign-to-merge-spread | ✅
⏣ ESLint | prefer-object-spread | ✅

remove-useless-array

The thing is [...b] can be used for:

- copying an array;
- converting different value type like string to an array.

So better to be more concrete and use slice for copying and Array()/Array.from() for converting to decrease cognitive load.
Also sometimes there is no need on any of this operations, and we can drop spread.

$3

`js
for (const a of [...b]) {}

const places = [...getPlaces()];
`

$3

`js
for (const a of b) {}

const places = getPlaces();

// Array constructor creates sparse array
[...Array(5)].map(Number);
`

remove-useless-object

$3

`js
const a = {
...fn(),
};
`

$3

`js
const a = fn();
`

nested

Checkout in 🐊Putout Editor.

$3

`js
[
...[
...a,
...b,
],
...x,
];
`

$3

`js
[
...a,
...b,
...x,
];
`

convert-apply-to-spread

> Spread syntax (...) allows an array expression to be expanded in places where zero or more arguments are expected.
>
> (c) MDN

$3

`js
console.apply(null, arguments);
`

$3

`js
console.log(...arguments);
``

License

MIT