cat.js

#!/usr/bin/env node

const fs = require('fs')


const fileinput = {
    /**
     * Basic behavior of python's method of the same name
     * @returns string[] lines of the file passed as an argument or piped
     */
    input: () => {
        const encoding = 'utf-8';
        const file = process.stdin.isTTY ? process.argv[2] : '/dev/stdin';
        const newline = line => `${line}\n`; // to keep the newlines
        const content = fs.readFileSync(file, encoding).split('\n');
        content.pop(); // somehow it reads a last empty line
        return content.map(newline);
    }
}


function main(file) {
    console.info(file.join(''))
}


if (require.main === module) {
    main(fileinput.input())
}

usage.md

Both print the content of the file.

cat file | cat.js
cat.js file