How make promise execute synchronously?

Question

I use dom-to-image.js for converting dom to png image. As dom-to-image.js uses promise, the code executes asynchronously. I want to execute .then function synchronously.

I have the following code:

domtoimage.toPng(document.getElementById("main")).then(function(dataUrl) {
    console.log(dataUrl);
}).catch(function(error) {
    console.error('oops, something went wrong!', error);
});

console.log("this console should be executed after console.log(dataUrl)")

I want to execute .then function first, before executing console.log("this console should be executed after console.log(dataUrl)").

Please tell me some way to achieve this.

Answer 1

There are of course legit reasons to force synchronous execution of a promise in js. The most obvious is when require'ing a file that needs to initialize using some asynchronous stuff, and optimization is not an overriding concern.

Seems like the package synchronized-promise seems like it ought to do the trick. In your case (warning - untested..):

const dti = () => docstoimage.toPng(document.getElementById("main"))
  .then(dataUrl => console.log('url: ', dataUrl))
  .catch(err => console.error('oops: ', err))

const sp = require('synchronized-promise')
const syncDti = sp(dti)
syncDti() // performs the 'synchronized version'

console.log("this console should be executed afterwards")

Answer 2

Try this:

async function doStuff(arg) {console.log(arg + "Assume this is a useful async function")}


doStuff.apply(/* What to specify as this */ this, /* List of args */ ["hello world "])