Project setup with create-svelte - Performance & Optimization

Performance: Project setup with create-svelte

MEDIUM IMPACT

This affects the initial page load speed and bundle size by determining which features and dependencies are included from the start.

Setting up a new Svelte project with create-svelte

Svelte

npm create svelte@latest my-app
# Choose only needed features, e.g., no TypeScript or testing if not required
npm install
npm run dev

Smaller dependency set and less code means faster bundle generation and quicker page load.

📈 Performance Gainsaves 150kb+ in bundle, reduces initial blocking time

Setting up a new Svelte project with create-svelte

Svelte

npm create svelte@latest my-app
# Select all optional features like TypeScript, ESLint, Prettier, Playwright, and testing
npm install
npm run dev

Including all optional features adds unnecessary dependencies and code, increasing bundle size and slowing initial load.

📉 Performance Costadds 200kb+ to bundle, blocks rendering longer during startup

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
Full feature setup with all options	Moderate (more components)	Multiple (due to complex styles)	High (larger CSS and JS)	[X] Bad
Minimal feature setup with only essentials	Low (fewer components)	Single or none	Low (smaller CSS and JS)	[OK] Good

Rendering Pipeline

The project setup determines which scripts and styles are included in the initial bundle. Larger bundles increase download and parse time, delaying Style Calculation and Layout stages.

→Network

→Style Calculation

→Layout

→Paint

⚠️ BottleneckNetwork and Style Calculation due to larger bundle and CSS

Core Web Vital Affected

LCP

This affects the initial page load speed and bundle size by determining which features and dependencies are included from the start.

Optimization Tips

1Choose only essential features during create-svelte setup to keep bundles small.

2Avoid adding unnecessary dependencies that increase load time.

3Use DevTools Network and Performance tabs to monitor bundle size and load speed.

Performance Quiz - 3 Questions

How does selecting all optional features during create-svelte setup affect performance?

A It decreases bundle size and speeds up load

B It has no effect on performance

C It increases bundle size and slows initial page load

D It only affects runtime memory, not load speed

DevTools: Network and Performance

How to check: Open DevTools, go to Network tab, reload page and check bundle size and load time. Then use Performance tab to record page load and see scripting and rendering times.

What to look for: Look for smaller JS and CSS files and shorter scripting and rendering blocks indicating faster load and paint.

Practice

1. What is the main purpose of running npm create svelte@latest?

easy

A. To update an existing Svelte project

B. To install Svelte globally on your computer

C. To start a new Svelte project with a ready setup

D. To run the Svelte development server

Solution

1. Step 1: Understand the command purpose

   npm create svelte@latest is used to create a new Svelte project, not to install or update globally.

2. Step 2: Differentiate from other commands

   Installing globally or running the server uses different commands like npm install -g or npm run dev.

3. Final Answer:

   To start a new Svelte project with a ready setup -> Option C

4. Quick Check:

   Create new project = A [OK]

Hint: Remember: 'create' means start new project [OK]

Common Mistakes:

• Confusing 'create' with 'install' globally
• Thinking it runs the app immediately
• Assuming it updates existing projects

2. Which command correctly installs the dependencies after creating a new Svelte project?

easy

A. npm run dev

B. npm create svelte@latest

C. npm start

D. npm install

Solution

1. Step 1: Identify the command for installing packages

   npm install downloads and installs all dependencies listed in package.json.

2. Step 2: Differentiate from other commands

   npm run dev starts the development server, npm create svelte@latest creates a project, and npm start is not standard here.

3. Final Answer:

   npm install -> Option D

4. Quick Check:

   Install dependencies = npm install [OK]

Hint: Install dependencies with 'npm install' before running app [OK]

Common Mistakes:

• Running 'npm run dev' before installing dependencies
• Confusing 'npm create' with install
• Using 'npm start' which may not be defined

3. After running npm create svelte@latest and npm install, what happens when you run npm run dev?

medium

A. It starts a local development server showing your Svelte app

B. It installs additional dependencies

C. It deletes the node_modules folder

D. It creates a new Svelte project

Solution

1. Step 1: Understand the role of 'npm run dev'

   This command starts the development server that hosts your Svelte app locally for testing.

2. Step 2: Clarify other options

   Installing dependencies is done by npm install, deleting folders is not part of this command, and project creation is separate.

3. Final Answer:

   It starts a local development server showing your Svelte app -> Option A

4. Quick Check:

   Run dev = start local server [OK]

Hint: Run 'npm run dev' to see your app live locally [OK]

Common Mistakes:

• Thinking 'npm run dev' installs packages
• Confusing it with project creation
• Expecting it to delete files

4. You ran npm create svelte@latest but forgot to run npm install. What will happen if you try npm run dev next?

medium

A. You get an error about missing dependencies

B. The development server starts normally

C. The project files get deleted

D. The app builds but shows a blank page

Solution

1. Step 1: Recognize the role of 'npm install'

   This command installs all needed packages. Without it, dependencies are missing.

2. Step 2: Predict the result of skipping install

   Trying to run the dev server without dependencies causes errors about missing modules.

3. Final Answer:

   You get an error about missing dependencies -> Option A

4. Quick Check:

   Missing install causes errors on run [OK]

Hint: Always run 'npm install' before 'npm run dev' [OK]

Common Mistakes:

• Assuming dev server runs without dependencies
• Expecting blank page instead of error
• Thinking files get deleted automatically

5. You want to create a new Svelte project with TypeScript support using npm create svelte@latest. Which step should you take during setup?

hard

A. Manually add TypeScript files after project creation

B. Choose the TypeScript template option when prompted

C. Run npm install typescript before creating the project

D. Skip dependency installation and add TypeScript later

Solution

1. Step 1: Understand create-svelte prompts

   When running npm create svelte@latest, it asks which features you want, including TypeScript support.

2. Step 2: Select TypeScript during setup

   Choosing the TypeScript option sets up the project with correct config and files automatically.

3. Step 3: Avoid manual or out-of-order steps

   Manually adding TypeScript or installing before project creation is unnecessary and error-prone.

4. Final Answer:

   Choose the TypeScript template option when prompted -> Option B

5. Quick Check:

   Select TypeScript at setup = A [OK]

Hint: Pick TypeScript option during create-svelte prompts [OK]

Common Mistakes:

• Adding TypeScript manually after setup
• Installing TypeScript before project creation
• Skipping dependency installation