nodejs sha256 implementation

sha256.js

#!/usr/bin/env node

// sha256.js by modrobert in 2024

"use strict";

const fs = require("fs");
const crypto = require("crypto");

if (process.argv.length === 2 || process.argv[2] === "-h") {
    console.error("usage; sha256.js <file> || -");
    process.exit(1);
}

let fileName = process.argv[2];

const sha256 = async (fileName) => {
    let input;
    if (fileName === "-") {
        input = process.stdin;
    } else {
        input = fs.createReadStream(fileName);
    }
    let hasher = crypto.createHash("sha256");
    for await (let chunk of input) {
        hasher.update(chunk);
    }
    return hasher.digest("hex");
};

sha256(fileName).then(hash => { console.log(hash); });

 $ time sha256.js ubuntu-22.04.3-desktop-amd64.iso 
a435f6f393dda581172490eda9f683c32e495158a780b5a1de422ee77d98e909

real	0m3.257s
user	0m2.938s
sys	0m1.428s

$ time /usr/bin/sha256sum ubuntu-22.04.3-desktop-amd64.iso 
a435f6f393dda581172490eda9f683c32e495158a780b5a1de422ee77d98e909  ubuntu-22.04.3-desktop-amd64.iso

real	0m14.767s
user	0m14.253s
sys	0m0.512s