Why you need to re-assign promises

reassigned.js

// Expected (and actual) output: 
// "first done"
// "hello world!"
let reassigned = Promise.resolve();
reassigned = reassigned.then(() => new Promise((resolve, reject) => { setTimeout(() => {console.log('first done'); return resolve("hello")}, 3000);}) );
reassigned.then((x) => new Promise((resolve, reject) => { console.log(`${x} world!`); resolve(`${x} world!`);}));

separate.js

// Expected output: 
// "first done"
// "hello world!"

//  Actual output: 
// "undefined world!"
// "first done"
let separate = Promise.resolve();
separate.then(() => new Promise((resolve, reject) => { setTimeout(() => {console.log('first done'); return resolve("hello")}, 3000);}) );
separate.then((x) => new Promise((resolve, reject) => { console.log(`${x} world!`); resolve(`${x} world!`);}));

thennable_promises_readme.md

This is an example of why you need to re-assign promises in a chain to keep the chain in order. They've been given different variables so you can copy & paste both examples into the same terminal.

Note: You'll need to hit <ENTER> again quickly to see the results properly.