> For the complete documentation index, see [llms.txt](https://bryan-guner.gitbook.io/my-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bryan-guner.gitbook.io/my-docs/redux/repos/examples/real-world/node_modules/concat-map.md).

# concat-map

## concat-map

Concatenative mapdashery.

[![browser support](http://ci.testling.com/substack/node-concat-map.png)](http://ci.testling.com/substack/node-concat-map)

[![build status](https://secure.travis-ci.org/substack/node-concat-map.png)](http://travis-ci.org/substack/node-concat-map)

## example

```js
var concatMap = require('concat-map');
var xs = [ 1, 2, 3, 4, 5, 6 ];
var ys = concatMap(xs, function (x) {
    return x % 2 ? [ x - 0.1, x, x + 0.1 ] : [];
});
console.dir(ys);
```

***

```
[ 0.9, 1, 1.1, 2.9, 3, 3.1, 4.9, 5, 5.1 ]
```

## methods

```js
var concatMap = require('concat-map')
```

### concatMap(xs, fn)

Return an array of concatenated elements by calling `fn(x, i)` for each element `x` and each index `i` in the array `xs`.

When `fn(x, i)` returns an array, its result will be concatenated with the result array. If `fn(x, i)` returns anything else, that value will be pushed onto the end of the result array.

## install

With [npm](http://npmjs.org) do:

```
npm install concat-map
```

## license

MIT

## notes

This module was written while sitting high above the ground in a tree.