TypeScript Lab: JSON Response

LAB / EXPLORATION

Planned

LAB 084 — Node HTTP & APIs
Send a structured JSON response from server to browser.

LAB TypeScript Lab: JSON Response Preview coming soon

LAB 084

TypeScript Lab: JSON Response

Concept

HTTP headers and JSON serialization define a machine-readable API response.

Concept

HTTP headers and JSON serialization define a machine-readable API response.

Objective & Explanation

What the project should make visible and why the concept matters.

Learning Target

Objective

Send a structured JSON response from server to browser.

Explanation

HTTP headers and JSON serialization define a machine-readable API response.

Project Plan

Structure, technologies, data boundary, and source connection.

Structure

project/
├── package.json
├── tsconfig.json
├── public/
│   ├── index.html
│   └── styles.css
└── src/
    └── server.ts

Technologies

TypeScript
Node.js
HTTP
HTML
CSS

Data Layer

No persistent data layer. Keep all demonstration values inside the standalone project.

Sandbox Source

src/local-editor/server.ts → sendJson()

Build Instructions

Build only the focused behavior, then use the visual layer to inspect it.

Setup

Create the standalone project folder and listed files.

Implement

Implement the smallest version that demonstrates the concept.

Run & Inspect

Use the interface to trigger and inspect the request/response behavior.

Code & Configuration

Starter configuration plus the focused implementation example.

Focused TypeScript

Implement this behavior first, then alter the input.

function sendJson(res: ServerResponse, status: number, body: unknown): void {
  res.writeHead(status, {
    "Content-Type": "application/json; charset=utf-8",
  });
  res.end(JSON.stringify(body));
}

Starter Configuration

Keep the project independently buildable.

package.json

{
  "type": "module",
  "scripts": {
    "build": "tsc",
    "start": "npm run build && node --enable-source-maps dist/server.js"
  },
  "devDependencies": {
    "@types/node": "^26.4.0",
    "typescript": "^7.0.2"
  }
}

tsconfig.json

{
  "compilerOptions": {
    "rootDir": "./src",
    "outDir": "./dist",
    "target": "ES2022",
    "module": "ES2022",
    "lib": ["ES2022", "DOM"],
    "types": ["node"],
    "strict": true,
    "sourceMap": true
  },
  "include": ["src/**/*.ts"]
}

Expected Visual Result

The output is the proof that the concept is working.

Visible Proof

The browser should visibly demonstrate: send a structured JSON response from server to browser.

Data: None