btn.addEventListener('click', downloadFile); ); The PDF may be > 20 MB. Using response.blob() after the full download is still streamed internally, but the code above keeps it simple. If you need true progressive streaming (e.g., showing a progress bar), replace the blob() call with the ReadableStream ‑based approach shown in the Advanced section at the end. 2️⃣ Back‑End – Flask API Endpoint Below is a minimal, secure, and testable Flask service that delivers the PDF. NOTE: If the PDF is copyrighted and not publicly licensed, you must enforce authentication or access‑control before serving it. The example includes a placeholder @login_required decorator you can swap for Flask‑Login, JWT, or any custom logic. 2.1 Project Layout project/ │ ├─ app/ │ ├─ __init__.py │ ├─ routes.py │ └─ utils.py │ ├─ static/ │ └─ pdf/ │ └─ GR-3108-Core.pdf ← (keep this outside public static!) │ ├─ requirements.txt └─ run.py 2.2 requirements.txt Flask==3.0.3 gunicorn==22.0.0 Werkzeug==3.0.3 (Add Flask-Login or PyJWT if you need auth.) 2.3 app/ init .py from flask import Flask from .routes import bp as api_bp
<button id="downloadBtn" class="btn btn-primary d-flex align-items-center" type="button"> <svg xmlns="http://www.w3.org/2000/svg" width="1em" height="1em" fill="currentColor" class="bi bi-download me-2" viewBox="0 0 16 16"> <path d="M.5 9.9a.5.5 0 0 1 .5.5v3.6c0 .28.22.5.5.5h13a.5.5 0 0 0 .5-.5V10.4a.5.5 0 0 1 1 0v3.6a1.5 1.5 0 0 1-1.5 1.5h-13A1.5 1.5 0 0 1 0 14V10.4a.5.5 0 0 1 .5-.5z"/> <path d="M7.646 1.146a.5.5 0 0 1 .708 0l3.5 3.5a.5.5 0 0 1-.708.708L8.5 2.707V11.5a.5.5 0 0 1-1 0V2.707L4.854 5.354a.5.5 0 1 1-.708-.708l3.5-3.5z"/> </svg> <span id="btnText">Download PDF</span> <span id="spinner" class="spinner-border spinner-border-sm text-light ms-2 d-none" role="status" aria-hidden="true"></span> </button> gr 3108 core pdf download
<script src="download.js"></script> </body> </html> /** * download.js – Handles click → fetch → save-as for GR‑3108‑Core.pdf * -------------------------------------------------------------- * 1. Calls /api/v1/download/gr-3108-core * 2. Streams response to avoid loading the whole file in RAM. * 3. Shows UI feedback (spinner, success/error message). * 4. Works on modern browsers (Chrome, Edge, Firefox, Safari). */ 2️⃣ Back‑End – Flask API Endpoint Below is
# 3️⃣ Production (Gunicorn) gunicorn -w 4 -b 127.0.0.1:8000 run:app Works on modern browsers (Chrome
