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Method Chaining ‚Äč

Elysia heavily encourages the use of method chaining.

Because Elysia's type system is complex, method usually introduce a new type to the instance.

Using method chaining will help save that new type refernce.

For example:

typescript
const app = new Elysia()
    .state('build', 1)
    // Store is strictly typed
    .get('/', ({ store: { build } }) => build)
    .listen(3000)
const app = new Elysia()
    .state('build', 1)
    // Store is strictly typed
    .get('/', ({ store: { build } }) => build)
    .listen(3000)

Using this, state now returns new ElysiaInstance type, introducing build into store and replace the current one.

Method chaining now save that new type and pass it to get, which is why get now have type access of build.

Without using method chaning, Elysia doesn't save the new type when introduced, leading to no type inference.

typescript
const app = new Elysia()

app.state('build', 1)

// Doesn't have access to build
app.get('/', ({ store: { build } }) => build)

app.listen(3000)
const app = new Elysia()

app.state('build', 1)

// Doesn't have access to build
app.get('/', ({ store: { build } }) => build)

app.listen(3000)

That's why Elysia encourage use of method chaining, not only that it reduce redundant usage of app. prefix, but also have better type inference.