Let me introduce the most complex front-end problem solved.
One of the most complex front-end issues is browser compatibility. Different browsers have different rendering methods for web pages, and compatibility needs to be handled for different browsers. In addition, front-end performance optimization is also a complex issue that requires comprehensive consideration of web page loading speed, rendering performance and other aspects.
Is the method of communication optimal? Various communication methods in vue
There is no absolute optimal solution for communication methods, but the most suitable method should be chosen according to the specific situation. In Vue, common communication methods include props and $emit, event bus, Vuex, etc. Each method has its own applicable scenarios, advantages and disadvantages, and you need to choose the appropriate communication method based on specific needs and project characteristics.
Provide and inject are not recommended by Vue. Can you guess why they are not recommended?
Provide and inject in Vue are a way for ancestor components to pass data to descendant components. Vue does not recommend this method because it will increase the coupling between components and reduce the reusability and maintainability of components.
The core concepts of vuex
The core concepts of Vuex include state, getters, mutations, actions, and modules. State is used to store the state of the application, Getters are used to derive new states, Mutations are used to modify the state, Actions are used to submit mutations, and Modules are used to divide the application state into modular parts.
Don’t you need to monitor the state of vuex yourself?
Vuex's state does not need to be monitored by itself. When the value of the state changes, Vue will automatically update the related views. This is because Vue uses a reactive system to track state changes and automatically trigger when the view needs to be updated.
What is a prototype and prototype chain?
A prototype is a property of an object in JavaScript that points to another object and is used to implement the inheritance relationship between objects. The prototype chain is a chain structure composed of the prototypes of multiple objects and is used to find the properties and methods of the object.
What are the changes in the diff algorithm of vue2 and vue3
The changes in the diff algorithm of Vue2 and Vue3 are mainly reflected in the following aspects: Vue3 uses Proxy objects to monitor data, which improves performance; the diff algorithm in Vue3 adopts an optimized strategy to reduce unnecessary DOM operations; Static nodes are optimized in Vue3 to improve rendering performance.
What is diff algorithm
Diff algorithm is an algorithm used to compare the differences between two tree structures. It is often used in virtual DOM (Virtual DOM) implementation in front-end frameworks or libraries. It compares the nodes of the old and new trees, finds the differences between them, and applies the differences to the real DOM to achieve efficient updating and rendering.
The core idea of the Diff algorithm is to compare the differences between them one by one by traversing the nodes of two trees. During the comparison process, the Diff algorithm will determine the type of node change based on the node type and attributes, such as the addition and deletion of nodes, changes in attributes, etc.
The Diff algorithm usually adopts the following optimization strategies to reduce the complexity of comparison and improve performance:
1. During the comparison process, if the types of two nodes are found Different, then the difference between them is completely different. There is no need to continue comparing their child nodes, and the entire node can be directly replaced.
2. During the comparison process, if the attributes of the two nodes are found to be different, then only the attributes need to be updated and their child nodes do not need to be compared.
3. When comparing child nodes, the Diff algorithm will use a strategy called "key" to determine the movement, insertion, and deletion of nodes by adding a unique identifier to each node.
Through the above optimization strategy, the Diff algorithm can efficiently find the differences between two trees and apply these differences to the real DOM, thereby achieving fast updating and rendering. This virtual DOM update method can avoid unnecessary DOM operations and improve the performance and user experience of front-end applications.
event loop
The event loop is a mechanism in JavaScript for handling asynchronous tasks. In the event loop, the JavaScript engine will continuously take out tasks from the task queue for execution. Tasks are divided into macro tasks and micro tasks. Macro tasks include setTimeout, setInterval, etc. Micro tasks include Promise, MutationObserver, etc.
Which one has higher priority, macro tasks or micro tasks?
Microtasks have higher priority than macrotasks. In each event loop, when all microtasks are executed, the next macrotask will be executed.
Is promise a macro task or a micro task?
Promises are microtasks. When the state of the Promise changes, it will be pushed into the microtask queue and executed immediately after the current macrotask is completed.
What are the advantages and disadvantages of client-side rendering and server-side rendering?
Both client-side rendering and server-side rendering have their own advantages and disadvantages. Client-side rendering refers to dynamically generating page content through JavaScript on the browser side. It has the advantages of good interactivity and good user experience, but the loading speed may be slow and is not friendly to search engine optimization. Server-side rendering refers to generating a complete HTML page on the server side and then sending it to the browser for display. The advantage is that it loads quickly and is friendly to search engines, but it is slightly less interactive.
What are the common configurations of webpack?
Common configurations of webpack include entry file configuration, output file configuration, module parsing configuration, plug-in configuration, etc. The entry file configuration specifies the entry file path of webpack; the output file configuration specifies the output file path and file name of webpack; the module parsing configuration specifies how to parse the path and file type of the module; the plug-in configuration is used to extend the functions of webpack.
What are the performance optimizations of webpack?
Webpack's performance optimization includes code splitting, lazy loading, caching mechanism, code compression, etc. Code splitting can split the code into multiple small files and load them on demand to improve page loading speed; lazy loading can delay loading of certain modules and reduce the number of resources initially loaded; the caching mechanism can use browser cache to reduce repeated loading of resources. ; Compressing code can reduce file size and improve loading speed.
Front-end performance optimization
Front-end performance optimization includes reducing HTTP requests, compressing files, using cache, asynchronous loading, optimizing images, etc. Reducing HTTP requests can reduce the number of requests by merging files, using sprite images, etc.; compressing files can reduce file size and improve loading speed; using caching can make use of browser cache to reduce repeated requests; asynchronous loading can load resources on demand, reducing The burden of initial loading; optimizing images can reduce image loading time by selecting appropriate image formats, compressing image sizes, etc.
How is the code managed?
Code can be managed through a version control system (such as Git), using branches to manage different functions or versions, and managing code changes through operations such as submission and merging. At the same time, the code can also be organized in a modular manner, dividing the code into different modules to improve the maintainability and reusability of the code.