Node.js ES6 Promises Example

promises.js

new Promise(function(resolve, reject) { 
	setTimeout(function() { 
	var firstVal = 1;
	// in the promise what you resolve is what gets returned
	resolve(firstVal); 
	console.log('the initial promise renders: ', firstVal); 
	}, 3000); // faking some longer process
})
.then(function(firstVal) { 
	var secondVal = firstVal + 1;
	console.log('the second function renders: ', secondVal); 
	return secondVal; 
})
.then(function(secondVal) {
	// note how each function uses a previous function's return value
	var thirdVal = secondVal + 1; 
	console.log('the third function renders: ', thirdVal); 
	return thirdVal; 
})
.then(function(thirdVal) {
	// note how each function uses a previous function's return value 
	var fourthVal = thirdVal + 1; 
	console.log('the last function renders: ', fourthVal);
});

/* the resulting output should be:

the initial promise renders:  1
the second function renders:  2
the third function renders:  3
the last function renders:  4

*/