Vue.js' internal rendering mechanism is the key to Vue.js' ability to provide efficient rendering performance and a responsive system. The internal rendering mechanism of Vue.js mainly involves the following aspects:
Virtual DOM
After the Vue.js template is compiled, a virtual DOM tree will be generated. This tree can be processed by the built-in rendering function of Vue.js, and finally mapped into a real DOM tree. A virtual DOM tree is a JavaScript object that can be modified again, such as adding, deleting, and replacing nodes, and can be compared and updated efficiently, reducing the performance overhead caused by direct manipulation of the DOM.
responsive system
Data hijacking is implemented through Object.defineProperty, which can automatically update the view when the data changes. When the data in the Vue instance changes, its corresponding virtual DOM node will change, triggering re-rendering, and finally updating the view. This process is called a "reactive system". The system can respond to data changes in real time very efficiently, reducing the repetitive operations of manually updating the DOM.
Asynchronous update queue
Vue.js adopts an asynchronous processing strategy, by "caching" a series of operations into the queue and executing them in the next "tick" idle time to reduce unnecessary repeated calculations and DOM operations. If the same data change is triggered multiple times in a row, Vue.js will only cache it once, avoiding repeated calculations. At the same time, Vue.js will prioritize asynchronous tasks to ensure that high-priority tasks are executed first, improving the performance and user experience of the entire application.
Component level updates
Vue.js regards each component as an independent entity, and the update corresponding to each component can be completed inside the component, avoiding unnecessary global refresh. Component-level updates also enable Vue.js to provide more efficient local updates, such as updating a single element in a list without having to re-render the entire list.
To sum up, the internal rendering mechanism of Vue.js is developed around key technical points such as virtual DOM, responsive system, asynchronous update queue and component-level updates, which can provide efficient rendering performance and responsive system, support rapid development and high Quality user experience.