4 finds an item in an array matching a predicate function,
7 fast both when `thisArg` is used and also when it isn't: [jsPerf](http://jsperf.com/array-prototype-findindex-shims)
11 npm install find-index
14 findIndex = require('find-index')
15 findLastIndex = require('find-index/last')
17 findIndex(array, callback[, thisArg])
18 findLastIndex(array, callback[, thisArg])
21 The array to operate on.
23 Function to execute on each value in the array, taking three arguments:
25 The current element being processed in the array.
27 The index of the current element being processed in the array.
29 The array findIndex was called upon.
31 Object to use as this when executing callback.
33 based on [array-findindex](https://www.npmjs.org/package/array-findindex)