generator.md

var x = 1

// define a generator 
function *foo() {
	x++;
	yield; // pause
	console.log("x: ", x);
}

// just an ordinary function that increments x 
function bar() {
	x++;
}

// create the iterator object to control the generator
var it = foo() 

// run the generator until the first yield (or the end of the function if there is no yield)  
it.next(); // start foo here
// note that it.next at this point returns {value: undefined, done: false}
// value is undefined because our generator is not returning anything

// at this point we check the value of x, which is incremented by 1 as expected 
x; // 2

// while the generator is paused, incrememnt x again
bar();

// continue running the generator (unpause) until the end (or until the next yield statement)
it.next(); 
// note that it.next at this point returns {value: undefined, done: true}

// x is logged to the console and it is incremented by 2. this is amazing :-D
x:  3