onRender

onRender is a callback function commonly found in frontend JavaScript frameworks and libraries. Its primary purpose is to execute custom logic immediately after a component or view has been rendered to the Document Object Model (DOM). This timing is crucial because it ensures that the elements targeted by the callback function are present and accessible in the browser's structure.

Developers often use onRender for tasks such as initializing third-party JavaScript plugins that require a DOM element to attach to, performing DOM manipulations that are not directly managed by the framework, setting up event listeners, or fetching data that depends on the initial rendered state of the component. The exact name of this callback can vary between different frameworks, with some using terms like componentDidMount in React, mounted in Vue.js, or onInit in certain Angular lifecycle hooks.

The onRender function is typically invoked once after the initial render. However, in some frameworks, similar hooks might be called again after subsequent re-renders if the component's state or props change, leading to a re-rendering of the UI. Understanding when and where to use onRender is essential for efficient and predictable application behavior, allowing developers to interact with the DOM at the appropriate moment in the component lifecycle. It provides a stable point to integrate external scripts or perform imperative DOM operations without interfering with the framework's declarative rendering process.