boxDownloadAllFilesInFolder.js

'use strict';
const box = require('box-node-sdk');
const fs = require('fs');
const util = require('util');
const path = require('path');
let configFile = fs.readFileSync('config.json');
configFile = JSON.parse(configFile);

let session = box.getPreconfiguredInstance(configFile);
let client = session.getAppAuthClient("enterprise");
client._useIterators = true;

let folderId = "43491738095";
let folderName;
let localFolderPath;
client.folders.get(folderId, null)
    .then((folderInfo) => {
        folderName = folderInfo.name;

        return client.folders.getItems(folderId, { limit: 1000 });
    })
    .then((folderItemsIterator) => {
        return autoPage(folderItemsIterator);
    })
    .then((folderItems) => {
        console.log(folderName);
        console.log(folderItems.length);
        let files = folderItems.filter((item) => {
            return item.type === "file";
        });
        console.log(files);
        localFolderPath = createLocalFolder(folderName);
        let downloadPromises = [];
        files.forEach((file) => {
            downloadPromises.push(client.files.getReadStream(file.id, null)
                .then((stream) => {
                    let output = fs.createWriteStream(path.join(localFolderPath, file.name));
                    stream.pipe(output);
                }));
        });
        return Promise.all(downloadPromises);
    })
    .then(() => {
        console.log("Downloaded all files...");
        console.log(fs.readdirSync(localFolderPath));
    });

function createLocalFolder(folderName) {
    let localFolderName = path.join(__dirname, folderName);
    try {
        fs.mkdirSync(localFolderName);
    } catch (e) {
        if (e.code === "EEXIST") {
            resetLocalFolder(localFolderName);
            fs.mkdirSync(localFolderName);
        } else {
            throw e;
        }
    }
    return localFolderName;
}

function resetLocalFolder(localFolderName) {
    if (fs.existsSync(localFolderName)) {
        fs.readdirSync(localFolderName).forEach((localFileName) => {
            console.log(localFileName);
            fs.unlinkSync(path.join(localFolderName, localFileName));
        });
        fs.rmdirSync(localFolderName);
    }
}

function autoPage(iterator) {
    let collection = [];
    let moveToNextItem = () => {
        return iterator.next()
            .then((item) => {
                if (item.value) {
                    collection.push(item.value);
                }
                if (item.done !== true) {
                    return moveToNextItem();
                } else {
                    return collection;
                }
            })
    }
    return moveToNextItem();
}