javascript - Use await outside async

Question

Is there a way to make the javascript await keyword work outside async functions? I would like to be able to freeze the entire call-stack (instead of just the rest of the async function), to be resumed once the particular promise returns a value. Sadly a powerful await like that is currently gimped or not implemented yet. I tried to make nodent.js work, but due to my custom loader and dynamic functions it's unfortunately impractical.

Answer 1

Is there a way to make the javascript await keyword work outside async functions?

Sadly, the answer is: No.

See the docs:

The await expression causes async function execution to pause, to wait for the Promise's resolution, and to resume the async function execution when the value is resolved. [emphasis added]

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/await

I would like to be able to freeze the entire call-stack (instead of just the rest of the async function), to be resumed once the particular promise returns a value.

But how could your promise return a value if the entire call-stack was frozen? It would be stuck forever.

More details

To use await you need to be inside async function.

At least you have to do:

async function main() {
  // use await here
}
main();

in your main code.

Or, using an IIFE - thanks to Robert Klep for the suggestion:

void async function main() {
    // use await here
}();

Or, if you like punctuation:

(async () => {
    // use await here
})();

Other options

There are some other options to handle concurrency in Node, like:

• https://www.npmjs.com/package/co
• https://www.npmjs.com/package/bluebird-co
• https://www.npmjs.com/package/async-co
• http://bluebirdjs.com/docs/api/promise.coroutine.html
• http://taskjs.org/

none of which will freeze the call stack, however, as it would have the same effect as running kill -STOP with your own process ID and waiting for the stopped process to resume itself.