First Code — REPL, Files & Globals — Flow Diagram — Node.js

From install to globals — your first Node workflow

flowchart TD
    A["<b>i · Install</b><br/>node + npm via LTS<br/>verify with node -v"]
      --> B["<b>ii · REPL</b><br/>node ↵<br/>one line at a time"]
    A --> C["<b>iii · File mode</b><br/>node app.js<br/>full file executed"]
    B --> D["<b>iv · Node runtime</b><br/>V8 + Node APIs<br/>(the 'superpowers')"]
    C --> D
    D --> E["<b>v · global</b><br/>setTimeout, console,<br/>fetch, setImmediate"]
    D --> F["<b>vi · globalThis</b><br/>universal reference<br/>(window ≡ global)"]
    D --> G["<b>vii · top-level this</b><br/>= module.exports ({})<br/>NOT global"]
 
    classDef setup fill:#f5efe1,stroke:#6a8a4f,stroke-width:2px,color:#1a1915;
    classDef run fill:#fdecd3,stroke:#c2410c,stroke-width:2px,color:#1a1915;
    classDef rt fill:#eaf2f8,stroke:#3a6ea5,stroke-width:2px,color:#1a1915;
    classDef global fill:#ece5f5,stroke:#6b46c1,stroke-width:2px,color:#1a1915;
    classDef gotcha fill:#fde8e8,stroke:#c53030,stroke-width:2px,color:#1a1915;
    class A setup
    class B,C run
    class D rt
    class E,F global
    class G gotcha

Install

Install the LTS build from nodejs.org — bundles Node + NPM. Verify with `node -v` / `npm -v`.
REPL

Interactive mode: type `node`, evaluate one line at a time. Great for quick experiments; nothing persists.
File mode

Write `app.js` in a folder, run with `node app.js`. The whole file executes top to bottom.
Node runtime

V8 engine + Node APIs (fs, http, net, os). Runs your code in either REPL or file mode.
global

Node's global object. Provides setTimeout, setInterval, setImmediate, console, fetch, queueMicrotask.
globalThis

ES2020 universal reference. In Node, `globalThis === global`. In browsers, `globalThis === window`.
top-level `this`

Trap: at the top level of a Node file, `this` is the empty `module.exports`, not the global object.

From install to globals — your first Node workflow

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