flatMap — the missing function for functional Node

Those who use underscorejs are often very sad, because there is no flatMap function.

So, ...

Usage

npm install flatmap

var flatMap = require('flatmap');

Just like map, flatMap accepts three arguments:

• the array to be traversed

• the iterator function, which is invoked with three parameters

  * `value` currently iterated
  * optional `index` of current iteration
  * and optional `array` being iterated
  

• the context value, which will be this inside the iterator function.

Example:

flatMap(['Hi', 'World'], function(word) {
  return word.split('');
});
// ['H', 'i', 'W', 'o', 'r', 'l', 'd']

The iterator function can return either a value (in that case it is simply appended to results) or an array (in that case the array is concatenated with results).

Returning null or undefined from iterator will append nothing to the results.

Heads up! This is not equivalent to _.compose(_.flatten, _.map), since nested sub-arrays are not flattened.

License

Copyright (C) 2013 Boris Okunskiy boris@okunskiy.name (MIT license)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.