diff --git a/sections/errorhandling/centralizedhandling.md b/sections/errorhandling/centralizedhandling.md
index b307fcdf..1d184626 100644
--- a/sections/errorhandling/centralizedhandling.md
+++ b/sections/errorhandling/centralizedhandling.md
@@ -13,7 +13,7 @@ Without one dedicated object for error handling, greater are the chances of impo
 // DAL layer, we don't handle errors here
 DB.addDocument(newCustomer, (error, result) => {
   if (error)
-    throw new Error("Great error explanation comes here", other useful parameters)
+    throw new Error('Great error explanation comes here', other useful parameters)
 });
 
 // API route code, we catch both sync and async errors and forward to the middleware
@@ -45,7 +45,7 @@ app.use(async (err, req, res, next) => {
 // DAL layer, we don't handle errors here
 DB.addDocument(newCustomer, (error: Error, result: Result) => {
   if (error)
-    throw new Error("Great error explanation comes here", other useful parameters)
+    throw new Error('Great error explanation comes here', other useful parameters)
 });
 
 // API route code, we catch both sync and async errors and forward to the middleware
diff --git a/sections/errorhandling/operationalvsprogrammererror.md b/sections/errorhandling/operationalvsprogrammererror.md
index fa98057b..69ccee2c 100644
--- a/sections/errorhandling/operationalvsprogrammererror.md
+++ b/sections/errorhandling/operationalvsprogrammererror.md
@@ -11,7 +11,7 @@ Distinguishing the following two error types will minimize your app downtime and
 
 ```javascript
 // marking an error object as operational 
-const myError = new Error("How can I add new product when no value provided?");
+const myError = new Error('How can I add new product when no value provided?');
 myError.isOperational = true;
 
 // or if you're using some centralized error factory (see other examples at the bullet "Use only the built-in Error object")
@@ -25,7 +25,7 @@ class AppError {
   }
 };
 
-throw new AppError(errorManagement.commonErrors.InvalidInput, "Describe here what happened", true);
+throw new AppError(errorManagement.commonErrors.InvalidInput, 'Describe here what happened', true);
 
 ```
 </details>
@@ -52,7 +52,7 @@ export class AppError extends Error {
 }
 
 // marking an error object as operational (true)
-throw new AppError(errorManagement.commonErrors.InvalidInput, "Describe here what happened", true);
+throw new AppError(errorManagement.commonErrors.InvalidInput, 'Describe here what happened', true);
 
 ```
 </details>
diff --git a/sections/errorhandling/testingerrorflows.md b/sections/errorhandling/testingerrorflows.md
index d079d2e3..552ca1f5 100644
--- a/sections/errorhandling/testingerrorflows.md
+++ b/sections/errorhandling/testingerrorflows.md
@@ -10,11 +10,11 @@ Testing ‘happy’ paths is no better than testing failures. Good testing code
 <summary><strong>Javascript</strong></summary>
 
 ```javascript
-describe("Facebook chat", () => {
-  it("Notifies on new chat message", () => {
+describe('Facebook chat', () => {
+  it('Notifies on new chat message', () => {
     const chatService = new chatService();
     chatService.participants = getDisconnectedParticipants();
-    expect(chatService.sendMessage.bind({ message: "Hi" })).to.throw(ConnectionError);
+    expect(chatService.sendMessage.bind({ message: 'Hi' })).to.throw(ConnectionError);
   });
 });
 ```
@@ -24,11 +24,11 @@ describe("Facebook chat", () => {
 <summary><strong>Typescript</strong></summary>
 
 ```typescript
-describe("Facebook chat", () => {
-  it("Notifies on new chat message", () => {
+describe('Facebook chat', () => {
+  it('Notifies on new chat message', () => {
     const chatService = new chatService();
     chatService.participants = getDisconnectedParticipants();
-    expect(chatService.sendMessage.bind({ message: "Hi" })).to.throw(ConnectionError);
+    expect(chatService.sendMessage.bind({ message: 'Hi' })).to.throw(ConnectionError);
   });
 });
 ```
@@ -40,11 +40,11 @@ describe("Facebook chat", () => {
 <summary><strong>Javascript</strong></summary>
 
 ```javascript
-it("Creates new Facebook group", () => {
+it('Creates new Facebook group', () => {
   const invalidGroupInfo = {};
   return httpRequest({
     method: 'POST',
-    uri: "facebook.com/api/groups",
+    uri: 'facebook.com/api/groups',
     resolveWithFullResponse: true,
     body: invalidGroupInfo,
     json: true
@@ -61,12 +61,12 @@ it("Creates new Facebook group", () => {
 <summary><strong>Typescript</strong></summary>
 
 ```typescript
-it("Creates new Facebook group", async () => {
+it('Creates new Facebook group', async () => {
   let invalidGroupInfo = {};
   try {
     const response = await httpRequest({
       method: 'POST',
-      uri: "facebook.com/api/groups",
+      uri: 'facebook.com/api/groups',
       resolveWithFullResponse: true,
       body: invalidGroupInfo,
       json: true
diff --git a/sections/errorhandling/useonlythebuiltinerror.md b/sections/errorhandling/useonlythebuiltinerror.md
index 8c59285a..b4b96fe4 100644
--- a/sections/errorhandling/useonlythebuiltinerror.md
+++ b/sections/errorhandling/useonlythebuiltinerror.md
@@ -9,7 +9,7 @@ The permissive nature of JavaScript along with its variety of code-flow options
 ```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?");
+    throw new Error('How can I add new product when no value provided?');
 
 // 'throwing' an Error from EventEmitter
 const myEmitter = new MyEmitter();
@@ -20,7 +20,7 @@ const addProduct = async (productToAdd) => {
   try {
     const existingProduct = await DAL.getProduct(productToAdd.id);
     if (existingProduct !== null) {
-      throw new Error("Product already exists!");
+      throw new Error('Product already exists!');
     }
   } catch (err) {
     // ...
@@ -33,7 +33,7 @@ const addProduct = async (productToAdd) => {
 ```javascript
 // throwing a string lacks any stack trace information and other important data properties
 if(!productToAdd)
-    throw ("How can I add new product when no value provided?");
+    throw ('How can I add new product when no value provided?');
 ```
 
 ### Code example – doing it even better
@@ -56,7 +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)
 ```
 </details>
 
@@ -85,7 +85,7 @@ export class AppError extends Error {
 
 // 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)
 ```
 </details>
 
diff --git a/sections/production/createmaintenanceendpoint.md b/sections/production/createmaintenanceendpoint.md
index 405ad5bc..2db04a8b 100644
--- a/sections/production/createmaintenanceendpoint.md
+++ b/sections/production/createmaintenanceendpoint.md
@@ -27,7 +27,7 @@ router.get('/ops/heapdump', (req, res, next) => {
 
     heapdump.writeSnapshot((err, filename) => {
         console.log('heapdump file is ready to be sent to the caller', filename);
-        fs.readFile(filename, "utf-8", (err, data) => {
+        fs.readFile(filename, 'utf-8', (err, data) => {
             res.end(data);
         });
     });
diff --git a/sections/production/setnodeenv.md b/sections/production/setnodeenv.md
index 00c46bd6..4c721fec 100644
--- a/sections/production/setnodeenv.md
+++ b/sections/production/setnodeenv.md
@@ -18,7 +18,7 @@ $ node
 
 ```javascript
 // Reading the environment variable using code
-if (process.env.NODE_ENV === "production")
+if (process.env.NODE_ENV === 'production')
     useCaching = true;
 ```
 
diff --git a/sections/projectstructre/separateexpress.md b/sections/projectstructre/separateexpress.md
index 16b48b1d..679b2a8b 100644
--- a/sections/projectstructre/separateexpress.md
+++ b/sections/projectstructre/separateexpress.md
@@ -13,8 +13,8 @@ The latest Express generator comes with a great practice that is worth to keep -
 ```javascript
 const app = express();
 app.use(bodyParser.json());
-app.use("/api/events", events.API);
-app.use("/api/forms", forms);
+app.use('/api/events', events.API);
+app.use('/api/forms', forms);
 ```
 
 ### Code example: Server network declaration, should reside in /bin/www
diff --git a/sections/security/sandbox.md b/sections/security/sandbox.md
index 366f8f03..34539566 100644
--- a/sections/security/sandbox.md
+++ b/sections/security/sandbox.md
@@ -11,22 +11,22 @@ As a rule of thumb, one should run his own JavaScript files only. Theories aside
 ### Code example - Using Sandbox library to run code in isolation
 
 ```javascript
-const Sandbox = require("sandbox");
+const Sandbox = require('sandbox');
 const s = new Sandbox();
 
-s.run("lol)hai", (output) => {
+s.run('lol)hai', (output) => {
   console.log(output);
   //output='Syntax error'
 });
 
 // Example 4 - Restricted code
-s.run("process.platform", (output) => {
+s.run('process.platform', (output) => {
   console.log(output);
   //output=Null
 });
 
 // Example 5 - Infinite loop
-s.run("while (true) {}", (output) => {
+s.run('while (true) {}', (output) => {
   console.log(output);
   //output='Timeout'
 });
diff --git a/sections/security/validation.md b/sections/security/validation.md
index 837a1d15..e37cdd37 100644
--- a/sections/security/validation.md
+++ b/sections/security/validation.md
@@ -30,7 +30,7 @@ Validation is about being very explicit on what payload our app is willing to ac
 ### Example - Validating an entity using JSON-Schema
 
 ```javascript
-const JSONValidator = require("jsonschema").Validator;
+const JSONValidator = require('jsonschema').Validator;
 
 class Product {
   
@@ -52,7 +52,7 @@ class Product {
 ```javascript
 // The validator is a generic middleware that gets the entity it should validate and takes care to return
 // HTTP status 400 (Bad Request) should the body payload validation fail
-router.post("/" , **validator(Product.validate)**, async (req, res, next) => {
+router.post('/' , **validator(Product.validate)**, async (req, res, next) => {
     // route handling code goes here
 });
 
diff --git a/sections/testingandquality/aaa.md b/sections/testingandquality/aaa.md
index 3a3acdf4..8678da7e 100644
--- a/sections/testingandquality/aaa.md
+++ b/sections/testingandquality/aaa.md
@@ -20,7 +20,7 @@ describe.skip('Customer classifier', () => {
     test('When customer spent more than 500$, should be classified as premium', () => {
         //Arrange
         const customerToClassify = {spent:505, joined: new Date(), id:1}
-        const DBStub = sinon.stub(dataAccess, "getCustomer")
+        const DBStub = sinon.stub(dataAccess, 'getCustomer')
             .reply({id:1, classification: 'regular'});
 
         //Act
@@ -38,7 +38,7 @@ describe.skip('Customer classifier', () => {
 ```javascript
 test('Should be classified as premium', () => {
         const customerToClassify = {spent:505, joined: new Date(), id:1}
-        const DBStub = sinon.stub(dataAccess, "getCustomer")
+        const DBStub = sinon.stub(dataAccess, 'getCustomer')
             .reply({id:1, classification: 'regular'});
         const receivedClassification = customerClassifier.classifyCustomer(customerToClassify);
         expect(receivedClassification).toMatch('premium');
diff --git a/sections/testingandquality/avoid-global-test-fixture.md b/sections/testingandquality/avoid-global-test-fixture.md
index 54fa0acc..92631c92 100644
--- a/sections/testingandquality/avoid-global-test-fixture.md
+++ b/sections/testingandquality/avoid-global-test-fixture.md
@@ -10,12 +10,12 @@
 
 ### Code example: each test acts on its own set of data
 ```javascript
-it("When updating site name, get successful confirmation", async () => {
+it('When updating site name, get successful confirmation', async () => {
   //test is adding a fresh new records and acting on the records only
   const siteUnderTest = await SiteService.addSite({
-    name: "siteForUpdateTest"
+    name: 'siteForUpdateTest'
   });
-  const updateNameResult = await SiteService.changeName(siteUnderTest, "newName");
+  const updateNameResult = await SiteService.changeName(siteUnderTest, 'newName');
   expect(updateNameResult).to.be(true);
 });
 ```
@@ -28,15 +28,15 @@ before(() => {
   //adding sites and admins data to our DB. Where is the data? outside. At some external json or migration framework
   await DB.AddSeedDataFromJson('seed.json');
 });
-it("When updating site name, get successful confirmation", async () => {
-  //I know that site name "portal" exists - I saw it in the seed files
-  const siteToUpdate = await SiteService.getSiteByName("Portal");
-  const updateNameResult = await SiteService.changeName(siteToUpdate, "newName");
+it('When updating site name, get successful confirmation', async () => {
+  //I know that site name 'portal' exists - I saw it in the seed files
+  const siteToUpdate = await SiteService.getSiteByName('Portal');
+  const updateNameResult = await SiteService.changeName(siteToUpdate, 'newName');
   expect(updateNameResult).to.be(true);
 });
-it("When querying by site name, get the right site", async () => {
-  //I know that site name "portal" exists - I saw it in the seed files
-  const siteToCheck = await SiteService.getSiteByName("Portal");
-  expect(siteToCheck.name).to.be.equal("Portal"); //Failure! The previous test change the name :[
+it('When querying by site name, get the right site', async () => {
+  //I know that site name 'portal' exists - I saw it in the seed files
+  const siteToCheck = await SiteService.getSiteByName('Portal');
+  expect(siteToCheck.name).to.be.equal('Portal'); //Failure! The previous test change the name :[
 });
 ```
\ No newline at end of file