hash.js

const fs = require('fs');
const md5 = require('md5');

const assets = [
    'css/styles.css',
    'js/scripts.js'
];

const dataFile = 'src/_data/hash.json';

const production = process.env.NODE_ENV === 'development' ? false : true;

let jsonValue = {};

assets.forEach((asset) => {
    if (production) {
        let file = '_site/' + asset;
        let fileHash = md5(fs.readFileSync(file)).substring(0, 15);

        let assetNameArray = asset.split('.');
        assetNameArray.splice(assetNameArray.length - 1, 0, fileHash);
        let hashedAsset = assetNameArray.join('.');


        fs.renameSync(file, '_site/' + hashedAsset);
        jsonValue[asset] = hashedAsset;
    } else {
        jsonValue[asset] = asset;
    }

});

fs.writeFileSync(dataFile, JSON.stringify(jsonValue));