# lazy-concat

> Lazily concat two arrays and exclude duplicate items at the joint, especially for sequential arrays.

Latest version **1.0.2** (published 2017-11-29) · MIT license · 0 weekly downloads

## Install

```sh
npm install lazy-concat
pnpm add lazy-concat
yarn add lazy-concat
bun add lazy-concat
```

## Health

**Score 20/100 (F)** — status: abandoned.

Positive: esm support; no vulnerabilities.

Warnings: low downloads; no types.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 1.0.2 |
| Published | 2017-11-29 |
| First published | 2017-11-29 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | none |
| Module format | ESM + CommonJS |
| Node | >=4 |
| Dependencies | 0 |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 0 |
| Author | kaelzhang |
| Maintainers | kael |
| Keywords | lazy-concat, concat, unique, union, array, duplicate, joint |

## Links

- npm: https://www.npmjs.com/package/lazy-concat
- Repository: https://github.com/kaelzhang/node-lazy-concat
- Homepage: https://github.com/kaelzhang/node-lazy-concat#readme
- Issues: https://github.com/kaelzhang/node-lazy-concat/issues
- npm.io page: https://npm.io/package/lazy-concat

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## Recent versions

- 1.0.2 (latest) — 2017-11-29
- 1.0.1 — 2017-11-29
- 1.0.0 — 2017-11-29

## README

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# lazy-concat

Lazily concat two arrays and exclude duplicate items at the joint, especially for sequential arrays.

## Install

```sh
$ npm install lazy-concat
```

## Usage

```js
import concat from 'lazy-concat'

concat([1, 2, 3], [2, 3, 9], 9, 10)
// 2 of the second array matches the second position of the first array
// concat([1, 2, 3], [2, 3, 9]) -> [1, 2, 3, 9]
// 9 matches the last item of the previously concat item
// -> [1, 2, 3, 9]
// 10 does not match,
// so the result is [1, 2, 3, 9, 10]

const concat2 = concat.factory({
  equal: (a, b) => a.i = b.i
})

concat2([{i: 1}, {i: 2}], [{i: 2}, {i: 3}])  
// [{i: 1}, {i: 2}, {i: 3}]

concat([1, 2, 3], [1, 9])
// 1 of the second array matches the first item of the first array,
// but the match is too deep
// which is deeper than the length of the second array.
// So the match will be rejected.
// And the result is `[1, 2, 3, 1, 9]`

concat(null, [1, 2])  // it will throw
```

## concat(...items)

- **items** `Array<any>` the first item should not be `null` or `undefined`, or it will throw an error.

Returns `Array`

## concat.factory({equal})

- **equal** `Function` the method to match items, by default:

```js
const equal = (a, b) => a === b
```

Returns `Function` the configured `concat` function.

## License

MIT

---
_Source: https://npm.io/package/lazy-concat · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._