learningGeneratorPromises.js

// helpers
function tryCatch(func, catcher) {
    try {
        func();
    } catch (err) {
        catcher(err);
    }
};

function makePromise(time) {
    return new Promise(function(resolve, reject) {
        setTimeout(() => resolve(`Time spent: ${time}`), time);
    });
};

// big deal!
function run(gen) {
    var it = gen.apply(this, Array.prototype.slice.call(arguments, 1));

    return new Promise(function (resolve, reject) {      
        (function go(next) {
            var handle = f => tryCatch(f, err => Promise.resolve(err).then(o => reject(o), r => reject(r)));
            
            Promise.resolve(next.value).then(
                v => handle(() => next.done ? resolve(v) : go(it.next(v))), 
                err => handle(() => next.done ? reject(err) : go(it.throw(err))));
        })(it.next());
    });
};

function *generator(value) {
    try {
        console.log(`---------- ${value} ----------`);
        console.log(yield makePromise(value * 5));
        console.log(yield value * 7);

        if (value >= 100) throw value;
        if (value >= 10) yield Promise.reject("reject");

        return "done";
    } catch (err) {  
        if (value >= 60) {
            yield Promise.reject(err);
        } else if (value >= 30) {
            throw err;
        } else if (value >= 15) {
            throw Promise.reject(`err: ${value}`);
        } else {
            return "it's ok";
        }
    }
};

// tests
function *test(num) {
    try {
        console.log(yield run(generator, num));
        console.log(yield run(generator, 1));
        console.log(yield "full test");
    } catch (err) {
        console.log(err);   
        console.log(yield "test catch");
    }
}

// test runner...
function *testRunner() {
    var nums = [ 100, 60, 30, 15, 10, 2 ];
    for (i in nums) {
        var num = Number(i) + 1;
        console.log(yield `############# Test ${num} : START`);
        yield run(test, nums[i]);
        console.log(yield `############# Test ${num} : END`);
        console.log();
    }
}

run(testRunner).catch(err => console.log(err));