Solution: I was passing the wrong variable into the http.get
Working code:
var file_url = 'http://.....',
DOWNLOAD_DIR = './location/';
esriAMD = ['one', 'two', 'three'..0;
function readFile(callback) {
if(esriAMD.length > 0) {
var setFile = esriAMD.shift(),
file_name = url.parse(setFile).pathname.split('/').pop(),
trial = setFile.split('/').pop(),
file = fs.createWriteStream(DOWNLOAD_DIR + trial);
http.get(file_url + setFile, function(res){
res.on('error', function(err){
console.log(err);
});
res.on('data', function(data){
file.write(data);
console.log(setFile + ' started');
});
res.on('end', function(){
console.log(setFile + ' completed, moving on');
});
});
} else {
callback();
}
}