Async function as plain function

async.function.as-plain-function.js

async function foo(args) {
  console.log('before await');
  const value = await 'b';
  console.log('after await', value);
  return value;
};

//Simplified version of async foo function 
function foo() {
   let resolve;
   let reject; 
   let value;

   const promisse = new Promise((_resolve, _reject) => {
     resolve = _resolve;
     reject = _reject;
   });

   function async_body(step) {
     switch (step) {
       case 0: { 
         console.log('before await');
         Promise.resolve('b').then(result => {
             value = result;
             async_body(step + 1);
           }, 
           error => reject(error)
         );
         break;
       }
       case 1: { 
         console.log('after await', value);
         resolve(value);
         break;
       }
     }
     default:
       resolve();  
   };
 
   try {
     async_body(0);
   } catch (e) {
     reject(e); 
   }
 
   return promisse;
}