How does reactivity work in Vue, and when is it useful to manually manipulate the DOM?

05 Ağu 04:34

In Vue 3, reactivity is based on `Proxy`: every time a property is accessed, a *dependency* is registered in the stack of effects running the render function. When that property changes, the proxy triggers a *trigger* that marks the component as "dirty" and schedules an update. On the next tick, Vue re-executes the render, generates a new V-DOM tree, and compares (patches) it with the previous one; only the nodes that actually differ are repainted in the real DOM, keeping performance high even with many state changes. In practice, I only avoid automatic reactivity when the cost of tracking mutations outweighs the benefit: for example, with large datasets (arrays of thousands of elements) that are only read or manipulated in blocks, with external libraries that handle their own DOM (like D3, Chart.js, or WYSIWYG editors), and with complex animations where Vue’s engine can’t optimize frames. In those cases, I use `ref`/`shallowRef` or `markRaw` to exclude the object from reactivity and then update the specific node with `nextTick` or `requestAnimationFrame`. This way, I keep the clarity of the reactive model where it adds value and cut overhead where manual DOM handling is more efficient.