findindex_polyfill_mdn

Code is from Mozilla findIndex() polyfill.

1. Require the npm module.

``js
npm install --save-dev findindex_polyfill_mdn
`

2. Include the file before the usage.

Then you need to require the file on your main.js or where you are
going to plan to use the find function as follows:

`js
require("findindex_polyfill_mdn")
``