After following, you can keep track of his dynamic information in a timely manner
background-image does not support native lazy loading because it is controlled by CSS and the browser does not track the load status. 1. Use IntersectionObserver to listen to elements to enter the viewport; 2. Store the image address through the data-bg attribute; 3. Load the picture after entering the visual area; 4. You can set rootMargin to load in advance; 5. You can add placeholder maps or animation optimization experience; 6. Pay attention to compatibility and performance, and control the number of listening.
Jul 31, 2025 am 04:14 AM
The choice of JSON or XML depends on the application scenario: 1. The situation of using JSON includes WebAPI return data, front-end interaction, modern service communication, and lightweight configuration; 2. The situation of using XML includes legacy system compatibility, namespace support, document-based data structures, and enterprise-level application interface specifications. In C#, .NETCore uses System.Text.Json for JSON serialization by default, with better performance and supports formatted output and null value retention; XML is implemented through XmlSerializer, suitable for old projects, and can customize tag names and namespaces, but does not support circular references, and needs to be processed manually or replaced with other libraries. Rationally select and configure serialization methods to help deal with different developments
Jul 31, 2025 am 04:12 AM
Database firewalls can effectively improve MySQL security. Specific methods include: 1. Use a whitelist mechanism to restrict access sources; 2. Intercept high-risk statements through SQL syntax analysis; 3. Implement user permission isolation strategies; 4. Set blacklist rules to block known attack modes; 5. Combining open source or commercial tools to achieve protection; at the same time, pay attention to rule configuration, log audit and performance evaluation, so as to ensure security without affecting normal business.
Jul 31, 2025 am 04:08 AM
Use chown to modify file ownership to pay attention to syntax and permissions. The basic format is sudochown[option] user file/directory, such as sudochownuser1example.txt or sudochownuser1:group1example.txt; modify directory and subcontent, you need to add -R parameters, such as sudochown-Ruser1:group1myfolder/; Common problems include forgetting to add -R, wrong operating system directory, and wrong colon position when modifying only users or groups; you can cooperate with find to accurately modify specific files, such as find/path/to/dir-typef-name"*.log&
Jul 31, 2025 am 04:05 AM
Use performance analysis tools to locate bottlenecks, use VisualVM or JProfiler in the development and testing stage, and give priority to Async-Profiler in the production environment; 2. Reduce object creation, reuse objects, use StringBuilder to replace string splicing, and select appropriate GC strategies; 3. Optimize collection usage, select and preset initial capacity according to the scene; 4. Optimize concurrency, use concurrent collections, reduce lock granularity, and set thread pool reasonably; 5. Tune JVM parameters, set reasonable heap size and low-latency garbage collector and enable GC logs; 6. Avoid reflection at the code level, replace wrapper classes with basic types, delay initialization, and use final and static; 7. Continuous performance testing and monitoring, combined with JMH
Jul 31, 2025 am 03:58 AM
The keyboard shortcuts for executing the current query are very practical and can significantly improve efficiency. Shortcut keys in common editors include: MySQLWorkbench (Ctrl Enter), DBeaver (Alt X or F8), SSMS (F5), VSCode (Shift Alt E), DataGrip/JetBrains (Ctrl Enter). To confirm the shortcut keys, you can view them through the menu bar, right-click menu or shortcut key prompt functions. Note when using: some tools need to select statements first, execute all content by default, and use Cmd instead of Ctrl on Mac. After mastering these techniques, you can complete the operation efficiently without switching the mouse frequently.
Jul 31, 2025 am 03:56 AM
TypenarrowingandtypeguardsenableTypeScripttosafelydeterminevariabletypeswithinspecificcodepathswhendealingwithuniontypes.1.Typenarrowingreducesavariable’spossibletypesbasedoncontrolflow,allowingsafeoperations.2.typeofguardsnarrowprimitivetypeslikestr
Jul 31, 2025 am 03:54 AM
To configure Nginx to support WebSocket connections, you need to set proxy parameters and pass the Upgrade and Connection headers correctly. 1. Add proxy_http_version1.1 in the location block and set Upgrade and Connection headers to complete protocol switching; 2. Adjust proxy_read_timeout and proxy_send_timeout to maintain long connections; 3. Use the upstream block to achieve load balancing of multi-backend servers, and enable keepalive connections to improve performance; 4. After the configuration is completed, use reload Nginx, verify handshakes with test tools and check logs to ensure configuration
Jul 31, 2025 am 03:50 AM
Selecting the right garbage collector is the first step in JavaGC tuning. Serial, Parallel, G1, ZGC or Shenandoah according to application needs; 2. Enable GC logs (Java8 uses -XX: PrintGCDetails, Java9 uses -Xlog) to collect GC behavior data; 3. Monitor key indicators such as pause time, GC frequency, heap usage trend, throughput and object promotion rate, and use tools such as gceasy.io to analyze logs; 4. For frequent young generation GCs, it can be solved by increasing the size of young generations or enabling adaptive strategies; 5. Long-term FullGC should be switched to G1, ZGC or Shenandoah to avoid display
Jul 31, 2025 am 03:35 AM
CustomHooksinReactarereusablefunctionsthatstartwith"use"andcanutilizebuilt-inHookstosharelogicacrosscomponents.1.Theyencapsulatebehaviorslikestatemanagement,sideeffects,ordatafetching,asseeninuseLocalStorageanduseFetchexamples.2.CustomHooks
Jul 31, 2025 am 03:35 AM
Using HTML5 semantic tags can improve page structure clarity, maintenance, SEO and accessibility. 1. It can be used multiple times to define the head and tail of a page or block; 2. It is designed for navigation and is suitable for main menus rather than all links; 3. It represents the main content of the page, with only one page and no duplicate elements; 4. It is used for independent content such as blogs, and is used to divide the logical blocks with titles. The rational use of these tags helps the code to be intuitive and easy to maintain.
Jul 31, 2025 am 03:35 AM
Selecting the Java SpringBoot React technology stack can build stable and efficient full-stack web applications, suitable for small and medium-sized to large enterprise-level systems. 2. The backend uses SpringBoot to quickly build RESTfulAPI. The core components include SpringWeb, SpringDataJPA, SpringSecurity, Lombok and Swagger. The front-end separation is achieved through @RestController returning JSON data. 3. The front-end uses React (in conjunction with Vite or CreateReactApp) to develop a responsive interface, uses Axios to call the back-end API, and ReactRouter
Jul 31, 2025 am 03:33 AM
The volatile keyword ensures the visibility of variables and prohibits instruction reordering in a multi-threaded environment. 1. Using volatile can ensure that one thread’s modification of variables is immediately visible to other threads, avoiding inconsistent values caused by CPU cache; 2. volatile prevents instruction reordering through happens-before rules, ensuring that modifications before write operations are visible to subsequent read operations; 3. It is suitable for simple scenarios such as status flags, such as shutdown flags; 4. However, it does not guarantee the atomicity of composite operations, such as count, still requires AtomicInteger or lock mechanism; 5. volatile cannot replace the synchronization mechanism to achieve complete thread safety. Therefore, volatile
Jul 31, 2025 am 03:32 AM
The weak type of PHP is a double-edged sword, which can both accelerate development and easily cause bugs. 1. Weak types allow variables to be automatically converted, such as $var=42 and can be changed to $var="hello"; 2. It supports rapid prototyping, but it is prone to errors caused by implicit conversion, such as "hello"==0 is true; 3. Solutions include using ===, type declaration, strict_types=1; 4. Modern PHP recommends type annotations, static analysis tools and strict modes to improve reliability; 5. The best practice is to combine flexibility and strong type control to ensure code maintainability. Therefore, weak types of power should be respected and used wisely.
Jul 31, 2025 am 03:32 AM
JMH is a framework for writing precise Java microbenchmarks that can avoid measurement deviations caused by JVM optimization. 1. Use Maven or Gradle to add jmh-core and jmh-generator-annprocess dependencies and enable annotation processing. 2. Write benchmark test methods and annotate configuration parameters with @Benchmark, @BenchmarkMode, @Warmup, @Measurement, @Fork, etc. 3. The return value of the time-consuming operation is prevented from being eliminated by JIT optimization through return or Blackhole.consume(). 4. Use @State(Scope.Thread) to define the status class
Jul 31, 2025 am 03:32 AM
PHP type conversion is flexible but cautious, which is easy to cause implicit bugs; 1. Extract the starting value when string is converted to numbers, and if there is no number, it is 0; 2. Floating point to integer truncation to zero, not rounding; 3. Only 0, 0.0, "", "0", null and empty arrays are false, and the rest such as "false" are true; 4. Numbers to strings may be distorted due to floating point accuracy; 5. Empty array to Boolean to false, non-empty is true; 6. Array to string always is "Array", and no content is output; 7. Object to array retains public attributes, and private protected attributes are modified; 8. Array to object to object
Jul 31, 2025 am 03:31 AM
Type prompts improve code readability and robustness. 1. It clarifies function parameters and return value types to reduce the understanding cost in collaboration; 2. The editor supports type prompts to provide better automatic completion and error prompts; 3. Supports complex types such as Union, Optional and container types through the typing module; 4. Type prompts should be used in combination with testing and review, and cannot replace runtime logical guarantees; 5. In the early stage, it can be gradually improved from the beginning of function signatures, and combined with Mypy and other tools to improve the effect.
Jul 31, 2025 am 03:29 AM
OracleSQL supports a variety of JOIN operations, including INNERJOIN getting matching rows, LEFTOUTERJOIN contains all rows on the left table, RIGHTOUTERJOIN contains all rows on the right table, FULLOUTERJOIN contains all rows on the two tables, CROSSJOIN generates Cartesian product, and SELFJOIN joins the table with itself. INNERJOIN only returns rows matching the two tables; LEFTOUTERJOIN returns all rows on the left table and the right table matching part, and NULL is displayed if there is no match; RIGHTOUTERJOIN is similar to LEFT but in the opposite direction; FULLOUTERJOIN returns all rows on the two tables and fills the mismatch part with NULL
Jul 31, 2025 am 03:24 AM
Add jackson-dataformat-xml and related dependencies; 2. Use XmlMapper to parse XML into JsonNode; 3. Use ObjectMapper to serialize JsonNode into JSON string; 4. Optionally remove root element wrapping by configuration or manual processing. This method uses the Jackson library to efficiently implement XML to JSON conversion, supports dynamic structure and is easy to integrate, and finally outputs formatted JSON results.
Jul 31, 2025 am 03:21 AM
When operating Elasticsearch in Python, you need to master the connection methods and common operations. 1. Install the elasticsearch library and establish a connection. Use Elasticsearch in the local environment (hosts=["http://localhost:9200"]); if security functions are enabled, you need to configure http_auth, use_ssl, and verify_certs. 2. Use the es.index() method to insert data. Elasticsearch can automatically create indexes, and you can also manually define the mapping control field type. 3. Query supports obtaining by ID through es.get() or constructing qu
Jul 31, 2025 am 03:19 AM
The challenges of handling big data coordination and scheduling can be solved through a combination of Python's tools. First, use Airflow to define DAG management task dependencies to realize task scheduling and process management; second, combine Celery to realize asynchronous processing and parallel execution of tasks; finally, use Dask to process large-scale data computing, and its interface is compatible with Pandas and supports distributed execution. These three can effectively respond to medium and large data processes.
Jul 31, 2025 am 03:19 AM
TooptimizeSSDperformanceonLinux,firstenableTRIMbycheckingsupportwithsudohdparm-I/dev/sdX|grepTRIM,thenensuretheweeklyfstrimtimerisactivewithsystemctlstatusfstrim.timer,orenableitmanuallyusingsudosystemctlenablefstrim.timer,andoptionallyusemanualtrimm
Jul 31, 2025 am 03:17 AM
Optimizing CPU usage requires monitoring utilization and adjusting priority, frequency strategy and binding core; 2. Memory optimization should reduce Swappiness, clean caches and rationally configure application memory; 3. Disk I/O optimization includes selecting appropriate scheduler, file system, mount options and RAID/LVM configuration; 4. Network tuning requires adjusting TCP parameters, enabling interrupt merging and balancing interrupt load; 5. System-level optimization recommends turning off redundant services, using chrony synchronization time and tuning kernel parameters, combining tools such as perf and sar to continuously analyze performance bottlenecks, and finally gradually improve system efficiency through baseline comparison, and fully realize stable and efficient operation of the server.
Jul 31, 2025 am 03:15 AM
When the MySQL database has insufficient disk space, you can check and clean it as follows: 1. Use df-h and du-sh/var/lib/mysql/* to check the usage of disk and MySQL files; 2. Clean the binary logs, delete the old logs by time or file name through PURGEBINARYLOGS, or set expire_logs_days automatically clean up in my.cnf; 3. Delete databases or tables that are no longer used, confirm that they are useless and make backups before executing DROPDATABASE or DROPTABLE; 4. Use OPTIMIZETABLE to recycle InnoDB tablespace fragments, be careful to reserve enough space to execute; 5. Deploy monitoring tools
Jul 31, 2025 am 03:13 AM
ES2023 has introduced 5 key features: 1. The findLast() and findLastIndex() methods can search elements from the end of the array; 2. WeakMap supports the registered symbol created using Symbol.for() as the key; 3. The #!hashbang syntax is officially supported, so that JavaScript scripts can be executed directly in the Unix-like system; 4. The error object supports cause attributes, which facilitates chain error traceability; 5. The with() method is added to the array, which can return the new array updated by the specified index without changing the original array. These improvements improve code readability, error handling capabilities and system compatibility. Although they are not revolutionary updates, they are effectively optimized
Jul 31, 2025 am 03:04 AM
Frameworksdonotautomaticallyensureaccessibility,sodevelopersmustintentionallyimplementsemanticHTML,ARIAroles,andkeyboardnavigation.2.InSPAs,manuallymanagefocusonroutechangesandmodalinteractionstosupportkeyboardandscreenreaderusers.3.UseARIAliveregion
Jul 31, 2025 am 02:57 AM
LPOP removes the element from the left side of the list and returns it, suitable for queues (FIFO); 1. RPOP operates from the right side, suitable for stacks (LIFO); 2. LPOP often builds queues with LPUSH, RPOP and LPUSH can implement stack structure; 3. Both are O(1) operations, empty list returns nil, and the original list will be modified unless a blocking variant is used.
Jul 31, 2025 am 02:55 AM
No,Navicatisnotthebestintermsofperformance;alternativeslikeDBeaver,HeidiSQL,andDataGripmayofferbetterperformance.1)DBeaverexcelswithlargedatasetsduetoefficienthandlingandJDBCoptimization.2)HeidiSQLisidealforMySQL,offeringfast,lightweightperformancean
Jul 31, 2025 am 02:53 AM
Use independent SSH keys: Generate an exclusive SSH key (such as personal and work) for each Git account and add it to SSHagent; 2. Configure the SSHconfig file: Set a custom host for different accounts in ~/.ssh/config (such as github.com-personal and github.com-work) to bind the corresponding key; 3. Update the repository remote URL: Use a custom host when cloning or setting remote to ensure that the correct key is automatically matched; 4. Set Git user information according to the repository: Delete the global user.name/email configuration, and execute gitconfig settings separately in each project.
Jul 31, 2025 am 02:45 AM
Best practices for configuring Redis include: 1. Set the bind address to 127.0.0.1, 2. Configure the requirepass password, 3. Set maxmemory to 512mb, 4. Enable AOF persistence and set appendfsync to everysec, 5. Enable protected-mode, 6. Set timeout to 300 seconds, 7. Configure slowlog to record slow commands, 8. Enable latency-monitor, 9. Set maxmemory-policy to allkeys-lru, 10. Use monitoring tools and keep Redis version updated.
Jul 31, 2025 am 02:42 AM
