Day 03 Routing

SvelteKit Routing

SvelteKit turns your file system into routes. Every +page.svelte is a route; every +layout.svelte wraps its children. Today you build a multi-page app with dynamic routes, nested layouts, and data loading.

~1 hour Day 3 of 5 Hands-on Precision AI Academy

Today's Objective

By the end of this lesson you will create static and dynamic routes in SvelteKit, pass route parameters to page components, share a persistent layout across routes, write a load function that fetches data before render, and handle 404 pages.

01

SvelteKit file-based routing

SvelteKit file-based routing is the foundation of Day 3. Every concept that follows builds on the mental model you establish here. The most effective approach is to understand the principle first, then apply it — skipping straight to implementation creates gaps that compound into confusion later.

Work through each example in this lesson sequentially. The concepts connect, and the order is deliberate. If something is unclear, slow down at that point rather than pushing past it — a ten-minute pause now saves hours of debugging later.

01
SvelteKit file-based routing
The core concept for today. Master this before moving to the next section.
02
load functions
The practical application that connects theory to working code.
03
page params
The integration step — where the day's concepts work together.
04
Common Errors
The mistakes that trip up beginners. Know them before you encounter them.
02

load functions in Practice

Understanding SvelteKit file-based routing requires seeing it in motion. The code below is not a complete application — it is a minimal, working illustration of the key mechanism. Study the pattern, run it, break it deliberately, then fix it. That cycle builds real comprehension.

Read before you run. Trace through the code mentally first. Identify what each section does. Then run it and compare your mental model to the actual output. The gap between expectation and result is where learning happens.

Once the basic pattern works, the logical next step is load functions. This is where the abstraction becomes useful — you move from understanding the mechanism to applying it to real problems. The transition is usually smaller than it feels. Most of the hard work happened in Section 1.

03

page params

page params completes today's picture. It is where SvelteKit file-based routing and load functions converge into a pattern you can apply to novel problems. This integration step is often where the day's learning consolidates — if the earlier sections felt abstract, this one typically makes them click.

Without load functions

Fragile and Incomplete

Implementing SvelteKit file-based routing alone handles the happy path. Real systems encounter edge cases, invalid input, and unexpected state. Missing load functions means missing those guards.

With load functions

Robust and Production-Ready

Combining SvelteKit file-based routing with load functions gives you a complete, defensible implementation. The extra lines cost ten minutes; the robustness they add is worth hours of debugging time.

Do not skip layouts. The final section of today ties the concepts together into a complete, tested implementation. Stopping early leaves you with fragments instead of a working mental model.
04

Common Errors and How to Avoid Them

Several mistakes appear consistently when engineers encounter SvelteKit Routing for the first time. Recognizing them now costs nothing; encountering them in production costs hours.

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Supporting Resources & Reading

Go deeper with these external references.

Day 3 Checkpoint

Before moving on, you should be able to answer these without looking:

Continue To Day 4
Server-Side Rendering