TypeScript Lab: Flatten Parent Tree

LAB / EXPLORATION

TypeScript Lab: Flatten Parent Tree

Planned

LAB 103 — Tree Structures
Move a parent under another parent while preserving two levels.

LAB TypeScript Lab: Flatten Parent Tree Preview coming soon

LAB 103

TypeScript Lab: Flatten Parent Tree

Concept

Flattening prevents deeper nesting by promoting existing children beside the moved node.

Concept

Flattening prevents deeper nesting by promoting existing children beside the moved node.

Objective & Explanation

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

Learning Target

Objective

Move a parent under another parent while preserving two levels.

Explanation

Flattening prevents deeper nesting by promoting existing children beside the moved node.

Project Plan

Structure, technologies, data boundary, and source connection.

Structure

project/
├── package.json
├── tsconfig.json
├── index.html
├── styles.css
├── data/
│   └── learning.db
└── src/
    ├── client.ts
    └── server.ts

Technologies

TypeScript
Node.js
SQLite
HTML
CSS

Data Layer

Use SQLite learning rows. Isolate destructive practice from important Sandbox records.

Sandbox Source

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

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

Render the returned or changed data in the browser.

Code & Configuration

Starter configuration plus the focused implementation example.

Focused TypeScript

Implement this behavior first, then alter the input.

for (const child of oldChildren) {
  database.prepare(`
    UPDATE content_nodes
    SET parent_id = ?, sort_order = ?
    WHERE id = ?
  `).run(targetParentId, nextOrder, child.id);
  nextOrder += 10;
}

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: move a parent under another parent while preserving two levels.

Data: SQLite