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- What properties does ajax have?
- The attributes of ajax include readyState, response, responseText, responseXML, status, statusText, timeout, onreadystatechange, onerror, onabort, onprogress, ontimeout, withCredentials, upload and onuploadprogress, etc.
- Front-end Q&A 1091 2023-11-17 11:38:00
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- What functions does ajax have?
- Ajax functions include XMLHttpRequest(), open(), send(), setRequestHeader(), getResponseHeader(), getAllResponseHeaders(), onreadystatechange, readyState, status, responseText, responseXML, statusText, onerror, etc.
- Front-end Q&A 930 2023-11-17 11:31:01
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- What technologies are there in ajax?
- Ajax technologies include XMLHttpRequest, JavaScript, DOM, CSS, XML, XSLT, callback functions, event processing, Promise, asynchronous programming, plug-ins and libraries, etc. Detailed introduction: 1. XMLHttpRequest, which is the core of AJAX. It is a JavaScript object used to send HTTP or HTTPS requests between the browser and the server; 2. JavaScript is the most commonly used programming language in AJAX, etc.
- Front-end Q&A 1230 2023-11-17 11:26:06
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- What frameworks are there for ajax?
- Ajax frameworks include jQuery, Axios, Fetch API, Ember.js, Backbone.js, Angular and React, etc. Detailed introduction: 1. jQuery is one of the most popular JavaScript libraries. It provides a concise and clear API to handle AJAX requests. jQuery also has a rich plug-in library that allows users to quickly implement complex functions; 2. Axios is A Promise-based HTTP client and more.
- Front-end Q&A 1375 2023-11-17 11:20:31
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- What are the parameters of ajax
- The parameters of ajax include url, type, async, timeout, cache, username, password, responseType, headers, data, success, error, beforeSend and complete, etc. Detailed introduction: 1. url, this is the target URL of the AJAX request, which is a string indicating the target address of the request; 2. type, this parameter specifies the type of AJAX request, etc.
- Front-end Q&A 2221 2023-11-17 11:05:03
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- When to use caching mechanism
- Situations when using the caching mechanism: 1. Improve access speed. The caching mechanism can store data that is frequently accessed or time-consuming to calculate the results so that it can be accessed quickly in the future. 2. Reduce network transmission. The caching mechanism can store data closer to the user. In order to reduce the delay and bandwidth consumption of network transmission; 3. Reduce the load of the server, the caching mechanism can reduce the load of the server and improve the throughput and scalability of the system; 4. Balance the system resources, the caching mechanism can balance the system Resource utilization between different components; 5. The caching mechanism can reduce system costs, etc.
- Front-end Q&A 1084 2023-11-16 17:23:00
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- What is the cache variable mechanism
- The cache variable mechanism is an optimization technology used to improve the performance and efficiency of programs. By using the cache variable mechanism, these calculation results can be stored in memory for direct use in subsequent calculations, thus saving calculation time and resources. Cache variables can store various types of data, including calculation results, database query results, network request results, etc. The cache variable mechanism can speed up program execution and improve user experience by reducing the number of repeated calculations and queries. But you need to pay attention to issues such as memory consumption and data consistency.
- Front-end Q&A 1804 2023-11-16 17:18:51
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- What are the methods of ajax request?
- The ajax request methods include XMLHttpRequest object, jQuery's ajax method, fetch method, axios library, Vue.js's axios method, Angular's HttpClient module, etc. Detailed introduction: 1. XMLHttpRequest object, which can send HTTP requests and receive responses; 2. jQuery's ajax method, by passing parameters, can send different types of requests, such as GET, POST, etc.
- Front-end Q&A 1583 2023-11-16 17:15:31
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- What are the components of ajax?
- The components of ajax include XMLHttpRequest object, JavaScript, XML, JSON, HTML, CSS, jQuery and so on. Detailed introduction: 1. XHR object, used to exchange data with the server in the background; 2. JavaScript, responsible for processing the data returned from the server and dynamically updating it to the page; 3. XML, which can structure the data transmission, so that the data can be parsed and processed; 4. JSON, the data can be transmitted in the form of key-value pairs, etc.
- Front-end Q&A 1423 2023-11-16 17:10:59
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- What are the limitations of ajax
- The limitations of ajax are: 1. Same-origin policy, Ajax requests can only be sent to URLs with the same protocol, domain name, and port number as the current page; 2. Asynchronous communication, when processing Ajax requests, developers need to process callback functions or use Asynchronous programming technologies such as Promise; 3. Indexability to search engines, search engine crawlers may not be able to detect content loaded through Ajax; 4. Browser compatibility, some older versions of browsers may not support certain Ajax functions; 5. Security. Real-time communication with the server has security risks.
- Front-end Q&A 1324 2023-11-16 17:01:38
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- What are the implicit casts?
- Implicit casts include: 1. Arithmetic type conversion; 2. Array and pointer type conversion; 3. Function parameter conversion; 4. Return value conversion; 5. Object inheritance and polymorphism; 6. Context-sensitive type conversion; 7 , Null value conversion; 8. Conversion from derived class to base class; 9. Conversion between values; 10. Cross-language type conversion; 11. Compatibility conversion; 12. Data type conversion during initialization. Although implicit type conversion can handle data type problems conveniently and quickly, it can also lead to some errors that are difficult to track down, especially in complex systems.
- Front-end Q&A 1542 2023-11-16 16:03:36
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- What are the caching mechanisms of search engines?
- The caching mechanisms of search engines include index caching, query caching, structured data caching, snapshot caching, real-time update caching, etc. Detailed introduction: 1. Index cache, the search engine will extract the keywords from the web page content and create an index so that the user can quickly find relevant web pages when searching; 2. Query cache, when the user enters a query statement, The search engine will first search the cache to see if there is a record of the same statement that has been queried before; 3. Structured data cache, the search engine will extract the structured data from the web page and store it in memory, etc.
- Front-end Q&A 1361 2023-11-16 15:10:03
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- How to implement lazy loading
- Methods to implement lazy loading include: 1. Intersection Observer API; 2. Dynamic Import; 3. Custom event listeners, etc. Detailed introduction: 1. The Intersection Observer API is an API provided by the browser, which can be used to monitor the positional relationship between elements and the viewport. When the element enters the viewport, the API will trigger a callback function, in which the loading of resources can be executed. Operation; 2. Dynamic Import, etc.
- Front-end Q&A 1116 2023-11-16 14:50:32
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- What are the http caching mechanisms?
- http caching mechanisms include cache headers, cache strategies, cache hits, cache invalidations, cache recycling, cache consistency, cache replacement strategies, proxy caching, browser caching, compression and encoding, CDN caching, etc. Detailed introduction: 1. Cache header, which is metadata contained in HTTP requests and responses, used to control cache behavior; 2. Cache policy, the web server uses the cache policy to determine how to handle the cache request; 3. Cache hit, when browsing When the browser requests the same resource again, if the resource is already available in the cache, the browser will directly retrieve it from the cache and so on.
- Front-end Q&A 1345 2023-11-16 10:48:13
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- What are the caching mechanisms?
- Caching mechanisms include memory cache, disk cache, network cache, database cache, CDN cache, reverse proxy cache, browser cache, etc. Detailed introduction: 1. Memory cache is a memory-based caching mechanism that stores frequently accessed data in the computer's memory to obtain and operate data faster; 2. Disk cache is a disk-based caching mechanism. Caching mechanism, which stores frequently accessed data on disk so that data can be obtained and manipulated faster during subsequent access; 3. Network caching, which is a caching mechanism based on network communication, etc.
- Front-end Q&A 1674 2023-11-15 17:53:19
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