Promise Examples

function firstThing() {
  return new Promise(function(resolve, reject){
      if (Math.random() > .5) {
          resolve("result1");
      } else {
          reject("fail1");
      }
  });
} 

function secondThing() {
  return new Promise(function(resolve, reject){
      if (Math.random() > .5) {
          resolve("result2");
      } else {
          reject("fail2");
      }
  });
} ;

function thirdThing() {
  return new Promise(function(resolve, reject){
      if (Math.random() > .5) {
          resolve("result3");
      } else {
          reject("fail3");
      }
  });
} 


//run functions in sequence
// firstThing()
// .then(result2 => secondThing(result2))
// .then(result3 => thirdThing(result3))
// .then(function(final) {
//     console.log(final)
// })
// .catch(function(err){
//     console.log(err)
// });

//run all function in parallel
// Promise.all([firstThing,secondThing,thirdThing]).then(function(){
//     console.log("all done.")
// });


// //first function to finish wins
Promise.race([firstThing, secondThing, thirdThing]).then(function(){
  console.log("first one wins.")
});