時代はECMAScript 2015（ES6）とはいえ、実はまだES5も追いかけられていない、使いこなせていない…という開発者も意外と多いのでは？ ES5のArray ...

In JavaScript, we use the filter method to filter items stored in an array using a callback. We use the map method to create a new array using the old array using the logic passed inside a callback.

Use popular 'grammar of data' syntax to filter and subset your two-dimensional JavaScript arrays and more. Here's how to use Arquero for data wrangling in Observable JavaScript and Node.js.