ExpressJS Advanced Topics in ExpressJS Syllabus

Advanced Topics in ExpressJS syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Advanced Topics in ExpressJS in ExpressJS, not a summary of it.

1. 1

   Template Engines

   3 topics

   • Using EJS
   • Using Pug
   • Using Handlebars
2. 2

   Database Integration

   3 topics

   • Connecting to MongoDB with Mongoose
   • Using SQL Databases
   • ORMs and ODMs
3. 3

   Authentication and Authorization

   3 topics

   • Using Passport.js
   • JWT Authentication
   • OAuth Integration
4. 4

   Security Best Practices

   3 topics

   • Securing Express Applications
   • Preventing Common Vulnerabilities
   • Using Helmet.js
5. 5

   Performance Optimization

   3 topics

   • Caching Strategies
   • Load Balancing
   • Profiling and Monitoring

Advanced Topics in ExpressJS flashcards for ExpressJS

18 of 50 cards from the Advanced Topics in ExpressJS deck — real questions with worked answers.

1. What is EJS in an Express.js application?

   EJS (Embedded JavaScript) is a templating engine that lets you generate HTML markup using plain JavaScript. It uses <% %> tags to embed logic and <%= %> to output escaped values into the page.

2. How do you configure Express to use EJS as its view engine?

   Set app.set('view engine', 'ejs') and place templates in a 'views' folder. You then render with res.render('template', dataObject), passing variables the template can access.

3. In EJS, what is the difference between the <%= %> and <%- %> output tags?

   <%= %> outputs a value with HTML escaping (safe against XSS), while <%- %> outputs the raw, unescaped value (used for injecting trusted HTML).

4. What distinguishes Pug from EJS as a templating engine?

   Pug uses a clean, indentation-based (whitespace-significant) syntax with no closing tags, whereas EJS embeds JavaScript directly into standard HTML. Pug compiles its terse syntax down to HTML.

5. How is a variable interpolated into text in a Pug template?

   Use #{variable} for escaped interpolation and !{variable} for unescaped interpolation. Attribute values can also use =, e.g. a(href=url).

6. What is Handlebars and what is its core design philosophy?

   Handlebars is a 'logic-less' templating engine that uses {{ }} mustache-style expressions. It minimizes in-template logic, favoring helpers and partials to keep templates clean and presentation-focused.

7. In Handlebars, what is the difference between {{expression}} and {{{expression}}}?

   {{expression}} HTML-escapes the output to prevent XSS, while {{{expression}}} (triple braces) renders the raw, unescaped HTML.

8. What are Handlebars partials used for?

   Partials are reusable template fragments (e.g. headers, footers) that can be included in other templates with the {{> partialName}} syntax, promoting DRY markup.

9. Compare EJS, Pug, and Handlebars on logic and syntax.

   EJS: full JavaScript logic embedded in HTML. Pug: indentation-based, terse, supports logic. Handlebars: logic-less mustache syntax relying on helpers/partials. EJS/Handlebars keep HTML-like markup; Pug replaces it with indentation.

10. What is Mongoose and what does it provide over the native MongoDB driver?

    Mongoose is an ODM (Object Data Modeling) library for MongoDB and Node.js. It provides schema definitions, model-based CRUD, validation, middleware/hooks, type casting, and query building on top of the raw driver.

11. How do you connect to MongoDB using Mongoose?

    Call mongoose.connect(uri) with a connection string like mongodb://localhost:27017/mydb (or a mongodb+srv Atlas URI). It returns a promise you await; the 'connected'/'error' events can also be listened to.

12. In Mongoose, what is the relationship between a Schema and a Model?

    A Schema defines the structure, field types, and validation rules of documents. A Model is a constructor compiled from a Schema (via mongoose.model('Name', schema)) that provides an interface to create and query documents in a collection.

13. What is the difference between an ORM and an ODM?

    An ORM (Object-Relational Mapper) maps objects to relational/SQL database tables and rows (e.g. Sequelize, TypeORM). An ODM (Object-Document Mapper) maps objects to document databases like MongoDB (e.g. Mongoose).

14. Name two popular ORMs used with Express and SQL databases.

    Sequelize and TypeORM (Prisma and Knex are also common). They map JavaScript/TypeScript objects and models to relational tables and handle queries and migrations.

15. What is the purpose of database migrations in an ORM workflow?

    Migrations are versioned scripts that incrementally apply and roll back schema changes (creating tables, altering columns), keeping the database schema in sync with the codebase across environments.

16. What are the main benefits of using an ORM/ODM instead of writing raw SQL?

    Benefits include schema validation, object-oriented data access, protection against SQL injection via parameterization, database-agnostic code, relationship management, and built-in migration tooling. Trade-offs are performance overhead and less fine-grained query control.

17. What is Passport.js and what is its core abstraction?

    Passport.js is authentication middleware for Node/Express. Its core abstraction is the 'strategy' — a pluggable module (e.g. local, JWT, OAuth) that defines how a request is authenticated.

18. In Passport.js, what do serializeUser and deserializeUser do?

    serializeUser determines which user data is stored in the session (typically the user id). deserializeUser takes that stored id on subsequent requests and retrieves the full user object, attaching it to req.user.

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