eachOfLimit-demo.js

let async = require('async')

function downloadSentinel(promObj) {

    return new Promise((resolve, reject) => {
        function makeRequest(url, i, callback) {
            var sys = require('util'),
                exec = require('child_process').exec,
                child;

            var directory = __dirname.substring(0, __dirname.indexOf("\\app_api"));

            console.log("executing:", directory + '\\downloadProducts.sh ' + promObj.ID[i] + ' ' + promObj.Name[i]);
            child = exec(directory + '\\downloadProducts.sh ' + promObj.ID[i] + ' ' + promObj.Name[i]);

            child.on("error", function (error) {
                console.log("child error:", error);
                callback(error);
            })

            child.stdout.on('data', function (data) {
                console.log(data.toString());
                callback();
            });

            child.on('exit', function (exit) {
                console.log("child exit:", exit);
                callback(exit);
            })
        }

        async.eachOfLimit(promObj.requestURLS, 2, makeRequest, function (err) {
            if (err) reject(promObj)
            else {
                resolve(promObj);
            }
        });
    });
}

let promObj = {
    requestURLS: ['url1', 'url2', 'url3'],
    ID: [1, 2, 3],
    Name: ["n1", "n2", "n3"]
}

downloadSentinel(promObj).then((res) => {
    console.log("THEN:", res)
}).catch((err) => {
    console.log("CATCH:", err) // err is the shell script exit code or shell stderr
})