In Vue, components are reusable building blocks for constructing user interfaces.
They allow us to encapsulate a piece of functionality and UI logic into a self-contained unit.
Components can be nested within each other to create complex UI structures.
Components in Vue can be defined in multiple ways, but one common approach is using Single File Components (SFCs), as shown in the previous response.
In addition to SFCs, we can also define components programmatically using JavaScript objects.
Template: Contains the HTML structure of the component.
JavaScript (Script): Contains the logic and data for the component.
Style: Contains CSS styles scoped to the component.
Vue.js provides a reactivity system that automatically updates the UI when the data changes.
This means that if the data used in a component's template changes, the UI will automatically reflect those changes without manual intervention.
Components can communicate with each other in several ways:
Props: Parent components can pass data down to child components via props.
Events: Child components can emit events to notify parent components about changes or actions.
EventBus: Vue instances can be used as a global event bus to facilitate communication between components that are not directly related.
Vuex: For more complex state management, we can use "Vuex", which provides a centralized store for all the components in our Vue application.
Vue.js provides a set of lifecycle hooks that allow us to execute code at specific stages of a component's lifecycle.
Lifecycle hooks:
beforeCreate: This hook is called synchronously immediately after the Vue instance has been initialized, before data observation and event/watcher setup. At this stage, the component has not yet been mounted to the DOM.
created: This hook is called synchronously after the Vue instance has been initialized and the component's data has been set up. However, the template has not yet been compiled or mounted to the DOM.
beforeMount: This hook is called right before the mounting `begins` the render function is about to be called for the first time.
mounted: This hook is called after the component has been mounted to the DOM. At this stage, the component's template has been rendered, and we can access the mounted DOM elements.
beforeUpdate: This hook is called before a component is updated, after data changes. It is called every time the component is re-rendered, but before the virtual DOM is patched.
updated: This hook is called after a component is updated, after the DOM has been re-rendered. At this point, we can access the updated DOM.
beforeDestroy: This hook is called right before a component is destroyed. At this stage, the component is still fully functional.
destroyed: This hook is called after a component has been destroyed. At this stage, all event listeners and child components have been removed.