2.3 KiB
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 bethis
inside theiterator
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.