Mastering JavaScript Functional Programming

Building pipelines by hand

Let's go with a Node.js example, similar to the command-line pipeline we built earlier in this chapter. We need a function to read all files in a directory and we can do that (in a not very recommendable way, because of the synchronous call, normally not good in a server environment) with something like this:

function getDir(path) {    const fs = require("fs");    const files = fs.readdirSync(path);    return files;}

Filtering the odt files is quite simple. We start with the following function:

const filterByText = (text, arr) => arr.filter(v => v.endsWith(text));

So, we can now write the following:

const filterOdt = arr => filterByText(".odt", arr);

Better still, we can applying currying, and go for pointfree style, as ...