inFureal

document.querySelector('div').dataset.dudu; // hello

const { src, dest, series } = require('gulp');
const glob = require("glob");
const fs = require('fs');

async function test1() {
    let res = null; // <===
    glob(__dirname + '/build/**/*.css', {}, (error, files) => {
        if (error) throw error;

        function readFiles() {
            let subarray = [];
            for (let name of files) {
                subarray = name.split();
                let globFile = subarray + '';
                let dateFiles = '';
                fs.readFile(globFile, "utf8",
                    function(error, data) {
                        if (error) throw error; 
                        res = data; // <===
                    })
            }
        }
        readFiles();
        log(readFiles());
    })
    return res; <===
}

exports.test1= series(test1);

const parent = () => {
    // ...
    try {
    fs.readFile(fileName, (err, content) => {
        if (err) {
            throw new Error();
        }
    })
    } catch (e) {
        return;
    }
   // ...
}

const parent = () => {
    // ...
    let success = true;
    fs.readFile(fileName, (err, content) => {
        if (err) {
            success = false;
            return;
        }
    })

     if (!success) return;
   // ...
}