Tutorials on Afterupdate

In Svelte, a component's afterUpdate lifecycle method is called after the component is updated as a result of a state change. When the value of any of a component's props and variables changes, the component's beforeUpdate lifecycle method is executed prior to any DOM updates being made in response to these changes. Once the beforeUpdate lifecycle method is finished running, the DOM is updated to reflect the data changes. After completing this update, the afterUpdate lifecycle method is executed. Being able to schedule a callback to run at this phase of a component's lifecycle ensures that the DOM is completely updated and synced with any new state and prop values. Here's a template of how the afterUpdate lifecycle method is used inside of a component: When using the afterUpdate lifecycle method, remember that it runs on every state and prop change. For components that experience many state and prop changes, it can be quite cumbersome to track which variables/props have changed in order to then execute the appropriate code. This is unlike React's componentDidUpdate lifecycle method , which provides the previous props and state as arguments.

Modern applications involve many DOM manipulations. Components (and elements) are constantly being removed, added, updated, etc. to deliver incredible user experiences and/or to optimize performance. Sometimes, you may need to execute code when a component is added (such as automatically focusing an input field when a form is loaded like the G-Mail login page) or when a component is removed (such as removing all event listeners associated with that element to prevent memory leaks). Frameworks/libraries such as React.js and Svelte provide component lifecycle methods that allow developers to predictably execute code at these very moments/situations. Having such access into each stage a component undergoes provides more control over how and when the component should be rendered. Commonly, functions can be scheduled to be invoked when these events occur in the lifecycle of a component instance: