learncodeacademy

##The Good, The Bad, & The Ugly Ways of handling Async Operations With Javascript## #####Callbacks < Promises < Generators#####

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###An Example: 5 in-sequence Async Operations### (also see parallel-sequence example: https://gist.github.com/willrstern/af3a3308fc5864cf48f8)

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###The Ugly Way: Callbacks### After each function takes place, handle any errors & do the next thing - It's easy to walk through the code and understand what's going on...but it's ugly as sin

learncodeacademy

##Example Task: Make 2 parallel (simultaneous) async calls, then one async call when they've resolved##

##The Good Way: Promises##

//with bluebird library
var parallelCalls = [
  getUrl('/api/profile'),
  getUrl('/api/accounts')
];
//spread is like .then(), except it apply()s the array of responses as individual arguments