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es6-bulletproof-async

  • A set of model code and examples that illustrates the es6-bulletproof pattern
  • A set of tips and techniques for coding asynchronous processes in ES6 Javascript so that
  • Indenting is eliminated and
  • error handling always conducts errors to the final .catch() in a Promise chain

Some code samples are available here es6 async tips examples

Fully working code example is available: Accounts List demo described here: Install and run

Install model code

Download zip or use npm

Download es6-bulletproof-async sample code

                                                                             
   $ npm install ingenious/es6-bulletproof-async

                                                                     
	// in root of folder
	$ npm install
	$ node accountsServer

should see

                                                                               
   SOAP service available on  http://127.0.0.1:5089/accountsList

Open another terminal window

                                                                     
	// in root of folder
	
	// accountId parameter can be varied
	$  node accountsClient  83684826432

Response

                                                                                     
{ accountId: '83684826432',
  accountsList:
   [ { sortCode: '44-44-44', accountNo: '2225927392' },
     { sortCode: '40-44-67', accountNo: '2224546392' } ] }

Request:
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Header/>
  <soap:Body>
    <ns1:AccountsRequest xmlns:ns1="http://example.com/accounts.xsd">
      <customerId>83684826432</customerId>
    </ns1:AccountsRequest>
  </soap:Body>
</soap:Envelope>

Response:
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Header/>
  <soap:Body>
    <AccountsList>
      <sortCode>44-44-44</sortCode>
      <accountNo>2225927392</accountNo>
    </AccountsList>
    <AccountsList>
      <sortCode>40-44-67</sortCode>
      <accountNo>2224546392</accountNo>
    </AccountsList>
  </soap:Body>
</soap:Envelope>

Creating ES6 'Bulletproof' asynchronous processes

Overview of pattern

  1. Have each step of the return a promise (facilitates unit testing and sharing)

  2. Wrap legacy callback handlers in Promise bodies in try { .. } catch(e){ resolve(e) }

  3. Add each step as an async method of a 'steps' class

  4. Add a final method which has the sequence logic laid out with await statements

  5. Return a Promise in .then() or catch() steps of a chain to ensure errors are passed down the chain

Benefits of pattern

  1. Syntax or processing errors are passed down the chain to be handled at the end of the chain

  2. By using class structures, data can be passed or cumulated through Promise chains in the this of the newed class

  3. Promises, functions, generators and static method can be mixed in the same structure

  4. await keyword allows linear sequences of async processes without need for indenting

  5. Code has enhanced readability

The pattern is fully explained in this document: ES6 async features in Node