gistfile1.js

(function(){

	function* test() {
		let data = yield getData();
		console.log(data);
		if(data > 30) {
			yield foo();
		} else {
			console.log("Fail");
		}
	}


	(function() {
		
		var start = function(foo){
			var iter;
			var proc = function(result) {
				result.value.then(function(value) {
					if(!result.done){
						proc(iter.next(value));
					}
				})
			}

			iter = foo();
			var next = iter.next();
			proc(next);
		}

		

		window.control = {
			start:start,
		};


	})();


	function getData() {
		return  new Promise(function(resolve, reject) {
			setTimeout(function(){
				resolve(50);
			}, 1000);
		});
	}

	function foo() {
		return  new Promise(function(resolve, reject) {
			setTimeout(function(){
				console.log("Completed");
				resolve();
			}, 2000)
		});
	}

	control.start(test);

})();