Promise chains

Promises.js

// case 1
new Promise((resolve, reject) => { throw new Error('fail'); })
.catch(err => { return Promise.reject(err); })
.then(val => console.log('[1] value: '+ val), err => console.log('[1] caught: ' + err.message));

// case 2
new Promise((resolve, reject) => { throw new Error('fail'); })
.catch(err => { throw err; })
.then(val => console.log('[2] value: '+ val), err => console.log('[2] caught: ' + err.message));

// case 3
new Promise((resolve, reject) => { throw new Error('fail'); })
.catch(err => { return err; })
.then(val => console.log('[3] value: '+ val), err => console.log('[3] caught: ' + err.message));

// case 4
new Promise((resolve, reject) => { throw new Error('fail'); })
.catch(err => { })
.then(val => console.log('[4] value: '+ val), err => console.log('[4] caught: ' + err.message));