sequential resolution of promises

sequentialPromises.js

var x = new Promise ((resolve,reject) => {
  setTimeout(() => {
    resolve(10)
  }, 200)
})
var y = new Promise ((resolve,reject) => {
  setTimeout(() => {
    resolve(2)
  }, 1000)

})
var z = new Promise ((resolve,reject) => {
  setTimeout(() => {
    resolve(3)
  }, 500)
})

var list = [x,y,z];

list.reduce((p, c) => {
  return p.then((val) => {
    console.log("intermediate val:", val);
    return c
  })
}, Promise.resolve(0))
.then((val) => {
  console.log("final value:", val)
})

// intermediate val: 0
// intermediate val: 10
// intermediate val: 2
// final value: 3