How can Async/Await be used to convert a callback-based image loading function into a promise-based approach for synchronous image data access?

Using Async/Await to Convert a Callback to a Promise

In JavaScript, the following function retrieves image data from a URL:

<code class="javascript">function getImageData(url) {
  const img = new Image();
  img.addEventListener('load', function() {
    return { width: this.naturalWidth, height: this.naturalHeight };
  });
  img.src = url;
}</code>

This function uses a callback approach, but it presents a limitation when trying to access the image data synchronously. If you were to invoke getImageData within the ready method as follows:

<code class="javascript">ready() {
  console.log(getImageData(this.url));
}</code>

you would obtain undefined since the image wouldn't have loaded yet. Therefore, it becomes necessary to utilize asynchronous techniques to handle the image loading operation before accessing the image data.

To achieve this, you can leverage the Promise constructor as follows:

<code class="javascript">function loadImage(url) {
  return new Promise((resolve, reject) => {
    const img = new Image();
    img.addEventListener('load', () => resolve(img));
    img.addEventListener('error', reject); // Handle error cases as well
    img.src = url;
  });
}</code>

Now, you can employ async/await to await the loadImage promise and subsequently retrieve the image data:

<code class="javascript">async function getImageData(url) {
  const img = await loadImage(url);
  return { width: img.naturalWidth, height: img.naturalHeight };
}

async function ready() {
  console.log(await getImageData(this.url));
}</code>

In this modified implementation, async/await ensures that the code pauses until the loadImage promise resolves, hence guaranteeing that the image data is available at the time of logging.

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