這個人不會寫 Promise 之討論串整理

00-這個人不會寫Promise.md

討論串來源: https://www.facebook.com/tomchentw/posts/1537332202978535

原始推文: Jason Miller 🦊⚛ on Twitter: "The web is getting async image decoding!"

01-OLD WAY.js

var image = new Image();
image.src = filename;
image.onload = function() {
  // use image
}

02-NEW WAY.js

fetch(filename).then(res => {
  res.blob().then(blob => {
    createImageBitmap(blob).then( image => {
      // use image
    }
  }
});

03-BETTER WAY.js

fetch(filename)
.then(res => res.blob())
.then(blob => createImageBitmap(blob))
.then(image => image.whatever());

04-EVEN-BETTER WAY.js

(async function aa() {
 var res = await fetch(filename);
 var blob = await res.blob();
 var image = await createImageBitmap(blob);
 console.log(image);
})();

05-EVEN-BETTER WAY (minified).js

(async function aa() {
  console.log(await createImageBitmap(await (await fetch(filename)).blob()))
})()

thx for recording.