To do what you want, using the fs.createWriteStream(path[, options]) function in a ES6 way:
const fs = require('fs');
const writeStream = fs.createWriteStream('file.txt');
const pathName = writeStream.path;
let array = ['1','2','3','4','5','6','7'];
// write each value of the array on the file breaking line
array.forEach(value => writeStream.write(`${value}\n`));
// the finish event is emitted when all data has been flushed from the stream
writeStream.on('finish', () => {
console.log(`wrote all the array data to file ${pathName}`);
});
// handle the errors on the write process
writeStream.on('error', (err) => {
console.error(`There is an error writing the file ${pathName} => ${err}`)
});
// close the stream
writeStream.end();