304 response, CORS problem: When there is no Access-Control-Allow-Origin header information, the 200 request returned last time shall prevail.
Example: may have been deleted
http://7af3zm.com1.z0.glb.clouddn.com/ajax_304_cors.html
Source code attached:
html
<!doctype html><html><head> <meta charset="UTF-8"></head><body><script type="text/javascript">// var _ajax_34re = false; function getAjax () { var _ajax_34re = false; if (_ajax_34re) { return _ajax_34re; } try { _ajax_34re = new XMLHttpRequest(); } catch (trymicrosoft) { try { _ajax_34re = new ActiveXObject("Msxml2.XMLHTTP"); } catch (othermicrosoft) { try { _ajax_34re = new ActiveXObject("Microsoft.XMLHTTP"); } catch (failed) { _ajax_34re = false; } } } return _ajax_34re; } function load(url) { request = getAjax (); request.open("GET", url); request.onreadystatechange = updatePage; request.send(null); } function updatePage() { if (request.readyState == 4) if (request.status == 200) alert("Server is done!" + request.responseText); else if (request.status == 404) alert("Request URL does not exist"); else alert("Error: status code is " + request.status); }</script><pre class="brush:php;toolbar:false"> access: 200、304响应都有 Access-Control-Allow-Origin:*; access-non: 200、304响应都 没 有 Access-Control-Allow-Origin; access-200: 200响应都有 Access-Control-Allow-Origin:*, 304响应 没 有 Access-Control-Allow-Origin;
What is the difference between an HTML tag and an HTML attribute?May 14, 2025 am 12:01 AMHTMLtagsdefinethestructureofawebpage,whileattributesaddfunctionalityanddetails.1)Tagslike,,andoutlinethecontent'splacement.2)Attributessuchassrc,class,andstyleenhancetagsbyspecifyingimagesources,styling,andmore,improvingfunctionalityandappearance.
The Future of HTML: Evolution and TrendsMay 13, 2025 am 12:01 AMThe future of HTML will develop in a more semantic, functional and modular direction. 1) Semanticization will make the tag describe the content more clearly, improving SEO and barrier-free access. 2) Functionalization will introduce new elements and attributes to meet user needs. 3) Modularity will support component development and improve code reusability.
Why are HTML attributes important for web development?May 12, 2025 am 12:01 AMHTMLattributesarecrucialinwebdevelopmentforcontrollingbehavior,appearance,andfunctionality.Theyenhanceinteractivity,accessibility,andSEO.Forexample,thesrcattributeintagsimpactsSEO,whileonclickintagsaddsinteractivity.Touseattributeseffectively:1)Usese
What is the purpose of the alt attribute? Why is it important?May 11, 2025 am 12:01 AMThe alt attribute is an important part of the tag in HTML and is used to provide alternative text for images. 1. When the image cannot be loaded, the text in the alt attribute will be displayed to improve the user experience. 2. Screen readers use the alt attribute to help visually impaired users understand the content of the picture. 3. Search engines index text in the alt attribute to improve the SEO ranking of web pages.
HTML, CSS, and JavaScript: Examples and Practical ApplicationsMay 09, 2025 am 12:01 AMThe roles of HTML, CSS and JavaScript in web development are: 1. HTML is used to build web page structure; 2. CSS is used to beautify the appearance of web pages; 3. JavaScript is used to achieve dynamic interaction. Through tags, styles and scripts, these three together build the core functions of modern web pages.
How do you set the lang attribute on the tag? Why is this important?May 08, 2025 am 12:03 AMSetting the lang attributes of a tag is a key step in optimizing web accessibility and SEO. 1) Set the lang attribute in the tag, such as. 2) In multilingual content, set lang attributes for different language parts, such as. 3) Use language codes that comply with ISO639-1 standards, such as "en", "fr", "zh", etc. Correctly setting the lang attribute can improve the accessibility of web pages and search engine rankings.
What is the purpose of HTML attributes?May 07, 2025 am 12:01 AMHTMLattributesareessentialforenhancingwebelements'functionalityandappearance.Theyaddinformationtodefinebehavior,appearance,andinteraction,makingwebsitesinteractive,responsive,andvisuallyappealing.Attributeslikesrc,href,class,type,anddisabledtransform
How do you create a list in HTML?May 06, 2025 am 12:01 AMTocreatealistinHTML,useforunorderedlistsandfororderedlists:1)Forunorderedlists,wrapitemsinanduseforeachitem,renderingasabulletedlist.2)Fororderedlists,useandfornumberedlists,customizablewiththetypeattributefordifferentnumberingstyles.
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software
EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function
Zend Studio 13.0.1
Powerful PHP integrated development environment
VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft
Dreamweaver Mac version
Visual web development tools
