convert-to-async

cta-async-await.js

app.post('/process-upload', upload.single('image'), async (req, res) => {
  // These helper methods aren't as necessary anymore, but they still
  // provide semantic value that makes the route easier to follow.
  const resizeAndConvert = buffer => (
    imConvertPromise({
      srcData: buffer,
      width: 32,
      height: 16,
      format: 'PNG'
    })
  );

  const readPixelsFromImage = buffer => (
    imageMagick.getConstPixels({
      srcData: buffer,
      x: 0,
      y: 0,
      columns: 32,
      rows: 16
    })
  );

  // Our saveToDisk method is now much more intuitive; no hidden complexity!
  const saveToDisk = (file, buffer) => (
    writeFilePromise(getPathForNewFile(file), buffer)
  );
  
  // Because this is native javascript, native constructs like try/catch,
  // `if` statements, and loops can be used!
  try {
    // The `await` keyword instructs the engine to wait, in a non-blocking
    // way, for the function to return before continuing.
    const originalFileBuffer = await readFilePromise(req.file.path);
    const smallFileBuffer = await resizeAndConvert(originalFileBuffer);

    await saveToDisk(req.file, smallFileBuffer);

    const pixels = readPixelsFromImage(smallFileBuffer);

    return res.json({ done: true, pixels });

  } catch (err) {
    throw err;
  }
});