promises.js

let aaa = () => {
  return new Promise((resolve, reject) => {
    console.log('aaa ');
    resolve('from_aaa');
  });
};

let bbb = (value) => {
  return new Promise((resolve, reject) => {
    console.log('bbb ' + value);
    resolve('from_bbb');
  });
};

let ccc = (value) => {
  return new Promise((resolve, reject) => {
    console.log('cccc ' + value);
    resolve('from_ccc');
  });
};
// -- code execute
aaa()
.then((value) => {
  // do nothing with value coming from aaa
  return bbb( 123 ); // call bbb() with custom parameter
})
.then( ccc );
/* results:
aaa
bbb 123
ccc from_bbb
*/
// -- trying to write it shorter...
aaa()
.then( bbb(123) )
.then( ccc );
/* results:
aaa
bbb 123       <-- this worked but the next one
ccc from_aaa  <-- this didn't, it grabbed
				  the value returned from aaa() instead of bbb()
*/