Download PDF from node API via FTP - node.js

Question

I have PDF on a remote server. I have API with node and I want, from my website, download the PDF.
I'm using jsftp to upload and read PDF. It works fine :
let str = '';
FTP.get('path/to/my/file', (err, socket) => {
socket.on("data", d => {
str += d.toString();
});
socket.on("close", err => {
if (err) {
console.error("There was an error retrieving the file.", err);
}
// HERE I HAVE THE FILE IN STRING
});
socket.resume();
});
On the close event I have the file in String, but I don't succeed to send it to the browser. I've tried things like :
let s = new Readable();
s.push(str);
s.push(null);
s.pipe(res);
OR
res.end(str);
But nothing happen in browser
I'm using Polymer for my ajax request
<iron-ajax
id="openPdf"
content-type="application/json"
method="POST"
url="/api/karaweb/pdf"
on-response="handleOpenPdfResponse"
on-error="errorMessage"></webservice-request>
Any solutions ?
Thanks

Answer 1

I have a mixin called PdfDownloaderMixin; here is the whole code:
<link rel="import" href="../../bower_components/polymer/polymer-element.html">
<dom-template id="pdf-downloader-mixin">
<script>
/* #polymerMixin */
const PdfDownloaderMixin = (superClass) => class extends superClass {
constructor() {
super();
}
downloadPdf(blobData) {
let fileObjectUrl = window.URL.createObjectURL(blobData);
window.open(fileObjectUrl);
}
}
</script>
</dom-template>
Then you use like this in your element:
<link rel="import" href="../../bower_components/polymer/polymer-element.html">
<link rel="import" href="../../bower_components/iron-ajax/iron-ajax.html" />
<link rel="import" href="pdf-downloader-mixin.html" />
<dom-module id="attachment-handler">
<template>
<iron-ajax id="getAttachmentAjax"
url="[[rootPath]]api/session/getattachment"
debounce-duration="300"
handle-as="blob"></iron-ajax>
</template>
<script>
class AttachmentHandler extends PdfDownloaderMixin(Polymer.Element) {
static get is() { return 'attachment-handler'; }
getAttachment() {
this.$.getAttachmentAjax.generateRequest().completes.then((req) => {
req.succeeded && this.downloadPdf(req.response);
});
}
}
customElements.define(AttachmentHandler.is, AttachmentHandler);
</script>
</dom-module>