Merge pull request #116 from AllenFang/master

prettify and unify the syntax

README.md

@@ -722,7 +722,8 @@ This repository is being kept up to date thanks to the help from the community.
 🌻 [Robert Manolea](https://github.com/pupix),
 🌻 [Xavier Ho](https://github.com/spaxe),
 🌻 [Aaron Arney](https://github.com/ocularrhythm),
-🌻 [Jan Charles Maghirang Adona](https://github.com/septa97)
+🌻 [Jan Charles Maghirang Adona](https://github.com/septa97),
+🌻 [Allen Fang](https://github.com/AllenFang)
 
 
 

sections/errorhandling/catchunhandledpromiserejection.md

@@ -11,8 +11,7 @@ Typically, most of modern Node.JS/Express application code runs within promises
 ### Code example: these errors will not get caught by any error handler (except unhandledRejection)
 
 ```javascript
-DAL.getUserById(1).then((johnSnow) =>
-{
+DAL.getUserById(1).then((johnSnow) => {
         //this error will just vanish
 	if(johnSnow.isAlive == false)
 	    throw new Error('ahhhh');
@@ -23,11 +22,11 @@ DAL.getUserById(1).then((johnSnow) =>
 ### Code example: Catching unresolved and rejected promises
 
 ```javascript
-process.on('unhandledRejection', function (reason, p) {
+process.on('unhandledRejection', (reason, p) => {
   //I just caught an unhandled promise rejection, since we already have fallback handler for unhandled errors (see below), let throw and let him handle that
   throw reason;
 });
-process.on('uncaughtException', function (error) {
+process.on('uncaughtException', (error) => {
   //I just received an error that was never handled, time to handle it and then decide whether a restart is needed
   errorManagement.handler.handleError(error);
   if (!errorManagement.handler.isTrustedError(error))
@@ -42,16 +41,16 @@ process.on('uncaughtException', function (error) {
  > Let’s test your understanding. Which of the following would you expect to print an error to the console?
 
 ```javascript
-Promise.resolve(‘promised value’).then(function() {
-throw new Error(‘error’);
+Promise.resolve(‘promised value’).then(() => {
+  throw new Error(‘error’);
 });
 
-Promise.reject(‘error value’).catch(function() {
-throw new Error(‘error’);
+Promise.reject(‘error value’).catch(() => {
+  throw new Error(‘error’);
 });
 
-new Promise(function(resolve, reject) {
-throw new Error(‘error’);
+new Promise((resolve, reject) => {
+  throw new Error(‘error’);
 });
 ```
 

sections/errorhandling/centralizedhandling.md

@@ -18,7 +18,7 @@ DB.addDocument(newCustomer, (error, result) => {
  
 //API route code, we catch both sync and async errors and forward to the middleware
 try {
-    customerService.addNew(req.body).then(function (result) {
+    customerService.addNew(req.body).then((result) => {
         res.status(200).json(result);
     }).catch((error) => {
         next(error)
@@ -29,7 +29,7 @@ catch (error) {
 }
  
 //Error handling middleware, we delegate the handling to the centralized error handler
-app.use(function (err, req, res, next) {
+app.use((err, req, res, next) => {
     errorHandler.handleError(err).then((isOperationalError) => {
         if (!isOperationalError)
             next(err);
@@ -47,14 +47,14 @@ function errorHandler(){
     this.handleError = function (error) {
         return logger.logError(err).then(sendMailToAdminIfCritical).then(saveInOpsQueueIfCritical).then(determineIfOperationalError);
     }
-
+}
 ```
 
 ### Code Example – Anti Pattern: handling errors within the middleware
 
 ```javascript
 //middleware handling the error directly, who will handle Cron jobs and testing errors?
-app.use(function (err, req, res, next) {
+app.use((err, req, res, next) => {
     logger.logError(err);
     if(err.severity == errors.high)
         mailer.sendMail(configuration.adminMail, "Critical error occured", err);

sections/errorhandling/shuttingtheprocess.md

@@ -13,22 +13,21 @@ Somewhere within your code, an error handler object is responsible for deciding
 //deciding whether to crash when an uncaught exception arrives
 //Assuming developers mark known operational errors with error.isOperational=true, read best practice #3
 process.on('uncaughtException', function(error) {
- errorManagement.handler.handleError(error);
- if(!errorManagement.handler.isTrustedError(error))
- process.exit(1)
+  errorManagement.handler.handleError(error);
+  if(!errorManagement.handler.isTrustedError(error))
+  process.exit(1)
 });
  
  
 //centralized error handler encapsulates error-handling related logic
 function errorHandler(){
- this.handleError = function (error) {
- return logger.logError(err).then(sendMailToAdminIfCritical).then(saveInOpsQueueIfCritical).then(determineIfOperationalError);
- }
+  this.handleError = function (error) {
+  return logger.logError(err).then(sendMailToAdminIfCritical).then(saveInOpsQueueIfCritical).then(determineIfOperationalError);
+}
  
- this.isTrustedError = function(error)
- {
- return error.isOperational;
- }
+this.isTrustedError = function (error) {
+  return error.isOperational;
+}
 
 ```
 

sections/errorhandling/testingerrorflows.md

@@ -11,11 +11,11 @@ Testing ‘happy’ paths is no better than testing failures. Good testing code
 
 ```javascript
 describe("Facebook chat", () => {
- it("Notifies on new chat message", () => {
- var chatService = new chatService();
- chatService.participants = getDisconnectedParticipants();
- expect(chatService.sendMessage.bind({message: "Hi"})).to.throw(ConnectionError);
- });
+  it("Notifies on new chat message", () => {
+    var chatService = new chatService();
+    chatService.participants = getDisconnectedParticipants();
+    expect(chatService.sendMessage.bind({ message: "Hi" })).to.throw(ConnectionError);
+  });
 });
 
 ```
@@ -24,14 +24,19 @@ describe("Facebook chat", () => {
 
 ```javascript
 it("Creates new Facebook group", function (done) {
- var invalidGroupInfo = {};
- httpRequest({method: 'POST', uri: "facebook.com/api/groups", resolveWithFullResponse: true, body: invalidGroupInfo, json: true
- }).then((response) => {
- //oh no if we reached here than no exception was thrown
- }).catch(function (response) {
- expect(400).to.equal(response.statusCode);
- done();
- });
- });
+  var invalidGroupInfo = {};
+  httpRequest({
+    method: 'POST',
+    uri: "facebook.com/api/groups",
+    resolveWithFullResponse: true,
+    body: invalidGroupInfo,
+    json: true
+  }).then((response) => {
+    //oh no if we reached here than no exception was thrown
+  }).catch(function (response) {
+    expect(400).to.equal(response.statusCode);
+    done();
+  });
+});
 
 ```

sections/errorhandling/usematurelogger.md

@@ -14,12 +14,12 @@ We all loovve console.log but obviously a reputable and persisted Logger like [W
 ```javascript
 //your centralized logger object
 var logger = new winston.Logger({
- level: 'info',
- transports: [
- new (winston.transports.Console)(),
- new (winston.transports.File)({ filename: 'somefile.log' })
- ]
- });
+  level: 'info',
+  transports: [
+    new (winston.transports.Console)(),
+    new (winston.transports.File)({ filename: 'somefile.log' })
+  ]
+});
 
 //custom code somewhere using the logger
 logger.log('info', 'Test Log Message with some parameter %s', 'some parameter', { anything: 'This is metadata' });
@@ -30,15 +30,19 @@ logger.log('info', 'Test Log Message with some parameter %s', 'some parameter',
 
 ```javascript
 var options = {
-    from: new Date - 24 * 60 * 60 * 1000,    until: new Date,    limit: 10,    start: 0,
-    order: 'desc',    fields: ['message']
-  };
+  from: new Date - 24 * 60 * 60 * 1000,
+  until: new Date,
+  limit: 10,
+  start: 0,
+  order: 'desc',
+  fields: ['message']
+};
 
 
-  // Find items logged between today and yesterday.
-  winston.query(options, function (err, results) {
-    //callback with results
-  });
+// Find items logged between today and yesterday.
+winston.query(options, function (err, results) {
+  //callback with results
+});
 
 ```
 

sections/errorhandling/useonlythebuiltinerror.md

@@ -14,19 +14,20 @@ From the blog Ben Nadel, ranked 5 for the keywords “Node.JS error object”
 
 ```javascript
 //throwing an Error from typical function, whether sync or async
- if(!productToAdd)
- throw new Error("How can I add new product when no value provided?");
+if(!productToAdd)
+    throw new Error("How can I add new product when no value provided?");
  
 //'throwing' an Error from EventEmitter
 const myEmitter = new MyEmitter();
 myEmitter.emit('error', new Error('whoops!'));
  
 //'throwing' an Error from a Promise
- return new promise(function (resolve, reject) {
-	Return DAL.getProduct(productToAdd.id).then((existingProduct) =>{
+return new Promise(function (resolve, reject) {
+    Return DAL.getProduct(productToAdd.id).then((existingProduct) =>{
 		 if(existingProduct != null)
-			 reject(new Error("Why fooling us and trying to add an existing product?"));
-
+			reject(new Error("Why fooling us and trying to add an existing product?"));
+    })
+});
 ```
 
 ### Code example – Anti Pattern
@@ -55,7 +56,7 @@ module.exports.appError = appError;
  
 //client throwing an exception
 if(user == null)
-  throw new appError(commonErrors.resourceNotFound, commonHTTPErrors.notFound, "further explanation", true)
+    throw new appError(commonErrors.resourceNotFound, commonHTTPErrors.notFound, "further explanation", true)
 ```
 
 

sections/production/bestateless.md

@@ -17,9 +17,9 @@ This approach:
 
 ```javascript
 //Typical mistake 1: saving uploaded files locally in a server
-var multer  = require('multer') //express middleware for fetching uploads
-var upload = multer({ dest: 'uploads/' })
-app.post('/photos/upload', upload.array('photos', 12), function (req, res, next) {})
+var multer  = require('multer'); //express middleware for fetching uploads
+var upload = multer({ dest: 'uploads/' });
+app.post('/photos/upload', upload.array('photos', 12), function (req, res, next) {});
 //Typical mistake 2: storing authentication sessions (passport) in a local file or memory
 var FileStore = require('session-file-store')(session);
 app.use(session({
@@ -27,7 +27,7 @@ app.use(session({
     secret: 'keyboard cat'
 }));
 //Typical mistake3: storing information on the global object
-Global.someCacheLike.result = {somedata}
+Global.someCacheLike.result = { somedata };
 ```
 
 <br/><br/>

sections/production/createmaintenanceendpoint.md

@@ -16,10 +16,10 @@ A maintenance endpoint is a plain secured HTTP API that is part of the app code
 var heapdump = require('heapdump');
  
 router.get('/ops/headump', (req, res, next) => {
-    logger.info(`About to generate headump`);
-    heapdump.writeSnapshot(function (err, filename) {
+    logger.info('About to generate headump');
+    heapdump.writeSnapshot((err, filename) => {
         console.log('headump file is ready to be sent to the caller', filename);
-        fs.readFile(filename, "utf-8", function (err, data) {
+        fs.readFile(filename, "utf-8", (err, data) => {
             res.end(data);
         });
     });