flush

import { flush } from "solid-js"

function flush(): void

flush() synchronously applies all pending reactive updates. In Solid 2.0, signal updates are batched by default via microtask scheduling — flush() forces those updates to apply immediately.

When to use

In most cases, you should let the default microtask batching handle updates. Use flush() only when you need to:

• Read DOM measurements immediately after a state change
• Ensure synchronous updates for testing
• Coordinate with external libraries that need immediate DOM state

const [count, setCount] = createSignal(0)

setCount(1)
setCount(2)
setCount(3)
// DOM hasn't updated yet — updates are batched

flush()
// Now all pending updates have been applied to the DOM

Replacing batch

flush() replaces batch() from Solid 1.x, but with inverted semantics. Where batch wrapped a block of updates to defer them, Solid 2.0 defers by default and flush forces synchronous application:

// 1.x — batch to defer
batch(() => {
  setA(1)
  setB(2)
})

// 2.0 — deferred by default, flush to force sync
setA(1)
setB(2)
flush() // only if you need synchronous DOM updates

Caution

Use flush() sparingly. Forcing synchronous updates bypasses the performance benefits of microtask batching. In most applications, the default behavior is sufficient.