Callbacks


function asyncMethod(message, callback_function) { 
  setTimeOut( function() {
    console.log(message);
    callback_function();
   }, 400)
}

asyncMethod('Connect to Database', function() {
}


Nested Callbacks


asyncMethod('Connect to Database', function() { 
  asyncMethod('Verify User Details', function() {
    asyncMethod('Check Permissions', function() {
      asyncMethod('Update User', function() {} )
    })
  })
})

Best Practices

Arguments should be (err, results)
Always 'return' when you want to exit



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