Detailed explanation of Vue operating mechanism: responsiveness, virtual DOM, componentization, asynchronous rendering

Detailed explanation of Vue operating mechanism: responsiveness, virtual DOM, componentization, asynchronous rendering

Vue is a popular JavaScript framework that provides a modern development method that allows us to more efficiently Build interactive front-end applications. The core idea of ​​Vue is "responsiveness", that is, changes in data can automatically update the view. This feature is based on Vue's design concept and operating mechanism. This article will introduce the operating mechanism of Vue in detail, including responsiveness, virtual DOM, componentization and asynchronous rendering.

1. Responsiveness

Vue’s responsive system allows data to automatically update the view, which is also the core design idea of ​​Vue. Specifically, Vue's responsive mechanism is implemented by hijacking data data through the Object.defineProperty() method. The hijacked object is called a "responsive object". It will automatically notify Vue when it is accessed or modified, and Vue will re-render accordingly.

The basic principle of the responsive mechanism is that when obtaining the attribute value of the responsive object, the attribute value will be collected into an observer list Watcher, and the Watcher will be notified when the attribute value changes, and the Watcher will notify Vue re-renders. This mechanism allows us to easily dynamically update data without directly manipulating the DOM.

2. Virtual DOM

Virtual DOM (Virtual DOM) is another important concept of Vue. It is a lightweight image of the real DOM, which can reduce the redrawing and rearrangement of the DOM. thereby improving performance. In Vue, when the data changes, Vue will re-render the virtual DOM based on the new data, then compare the differences between the old and new virtual DOM, and finally update only the parts of the real DOM that need to be updated.

By establishing a virtual DOM data structure, Vue encapsulates the nested relationships, properties, events and other properties of the real DOM into virtual DOM nodes, and then simulates the operations of the real DOM in the virtual DOM. After modifying the virtual DOM, by comparing the differences between the old and new virtual DOM, repeated modifications to the real DOM are avoided, thereby improving application performance.

3. Componentization

Vue’s componentization is an important means of building large-scale applications. It can split an application into multiple independent and reusable modules. In Vue, components are the basic units that constitute applications. Each component has its own state, methods, and views. It can encapsulate and manage internal states by itself and implement complex functions.

The component-based design allows developers to better manage the complexity of large-scale applications. Communication between components is completed using props and events, which makes the application more stable and easier to maintain. The idea of ​​componentization is also in line with the "bottom-up" design idea advocated by the Vue development team, that is, starting from small components and gradually assembling them into complex applications.

4. Asynchronous rendering

Vue’s asynchronous rendering is used to improve the performance of large applications. It puts the calculation process of virtual DOM updates into an asynchronous queue for execution, thus avoiding the need for synchronization. Blocking the main thread during rendering improves the response speed of the application. Vue implements asynchronous rendering by performing the following steps:

1. Add the components that need to be updated to the asynchronous queue;
2. Clear all components in the asynchronous queue at the next tick;
3. Before clearing the asynchronous queue, if the component that needs to be updated is added repeatedly, it will only be updated once;

The asynchronous rendering mechanism enables Vue to optimize performance, and for application development For readers, it does not need to care whether it is synchronous or asynchronous rendering, it only needs to operate the data, and Vue will automatically optimize performance according to the current rendering mechanism.

Summary

The above is the operating mechanism of Vue, including responsiveness, virtual DOM, componentization and asynchronous rendering. Responsiveness and virtual DOM are the core ideas of Vue. They can elegantly solve the redrawing and reflowing problems in front-end development, making the application smoother. Componentization and asynchronous rendering are further optimization solutions for Vue. They make it easier for us to develop large applications and improve application performance.

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