generators-magic.js

function async(genFunc) {
    const genObj = genFunc();
    const firstNext = genObj.next()
    log(firstNext)
    step(firstNext);

    function step({value,done}) {
        if (!done) {
            // A Promise was yielded
            value
            .then(result => {
                const secondNext = genObj.next(result)
                log(secondNext)
                step(secondNext)
            })
            .catch(error => {
                step(genObj.throw(error));
            });
        }
    }
}

var p1 = Promise.resolve(3);
var p2 = 1337;
var p3 = new Promise(function(resolve, reject) {
  setTimeout(() => {resolve('foo')}, 1000);
});

async(function* () {
    try {
        // yield == await
        const [val1, val2, val3] = yield Promise.all([
          p1,p2,p3
        ]);

        log(val1);
        log(val2);
        log(val3);
    } catch (e) {
        log('Failure to read: ' + e);
    }
});


function log (something) {
  console.log(something);
}