How to Fix Vue Watch Flush Timing

The Problem

In this quick-fix, you will learn controlling when watchers fire with flush. This matters because flush controls watcher timing post vs sync vs pre. In real-world applications, this pattern appears in DOM updates after state changes.

The Wrong Way

watchEffect(() => {
  console.log(el.value?.offsetHeight);
}); // May run before DOM update

Incorrect implementation

The Right Way

watchEffect(() => {
  console.log(el.value?.offsetHeight);
}, { flush: "post" }); // Runs after DOM update

Correct implementation with Composition API

Prevention

• Always use the official API
• Follow Vue best practices
• Test your implementation
• Document your patterns

FAQ

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