Backend development

Stage 1 · Lesson 2 of 10

JavaScript essentials

Your language and how HTTP works

is with types added, so learn the JavaScript underneath first. Focus on what backend code uses every day. That means const and let for variables, objects and arrays, and and spread for pulling values out and copying them.

It also means array methods such as map, filter and reduce, closures, classes, and JSON.parse and JSON.stringify. A closure is a function that remembers the variables around it when it was created. Learn the equality rules too.

=== compares values without converting their types, while == converts types first, in ways you will not want. Run everything with node from the terminal rather than in a browser.

Common trapskipping straight to a framework, then being lost when an error mentions this, undefined or a closure capturing the wrong variable. Those are JavaScript questions, and no framework answers them for you.

A question to check yourself, an AI practice session and 1 cheat sheet entry come with the full roadmap. Unlock

Resources for this stage

Start with· follow one of these

  • CoursePaid
    Grokking JavaScript Fundamentals

    Design Gurus · Beginner · $50

    JavaScript itself in a sensible order: scope, closures, promises and async code

  • GuideFree
    Node.js Learn

    OpenJS Foundation · Beginner

    Official guides on the event loop, async work, the http module and environment variables

Practise

  • Exercism

    Your language track: small exercises with free mentor feedback on idiomatic code

Keep handy

  • The TypeScript Handbook

    Read Everyday Types and Narrowing first, then keep it open while you write TypeScript

  • MDN Web Docs

    Read the HTTP overview, methods, headers and status code pages until they feel obvious

Also worth your time

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