HTML5 storage types: 1. Local storage "localstorage", suitable for long-term storage of data; 2. Local storage "sessionstorage", the stored data is automatically deleted after the browser is closed; 3. Offline cache "application" cache", locally cache files required by the application.
The operating environment of this tutorial: Windows 7 system, HTML5 version, Dell G3 computer.
Before h5, cookies were mainly used for storage. The disadvantage of cookies is that they carry data in the request header, and the size is within 4k. Main Domain pollution.
Main applications: shopping cart, customer login
For IE browser, there is UserData, the size is 64k, only IE browser supports it.
HTML5 provides two new methods of storing data on the client side:
- localStorage - data storage without time limit
- sessionStorage - data for a session Storage
1. Local storage localstorage
The data stored by the localStorage method has no time limit. The data is still available after the next day, week or year.
localStorage: suitable for long-term storage of data, the data will not be lost after the browser is closed;
Storage method:
With key-value pairs (Key- Value), it is stored permanently and will never expire unless manually deleted.
Size:
5M per domain name
Support:
Note: IE9 localStorage does not support local files. You need to deploy the project to the server to support it!
Detection method:
if(window.localStorage){
alert('This browser supports localStorage');
}else{
alert('This browser does NOT support localStorage');
}Commonly used API:
getItem //Get record
setIten//Set record
removeItem//Remove record
key//Get The value corresponding to the key
clear//Clear the content stored in the record
##:
Array, picture, json, style, script. . . (As long as the content can be serialized into a string, it can be stored) 2. Local storage sessionstorageThe localStorage and sessionStorage in the local storage API of HTML5 are the same in usage. The difference is The reason is that sessionStorage is cleared after closing the page, while localStorage will always be saved. 3. Offline cache (application cache) HTML5 introduces the application cache, which can cache the web and use it when there is no network. Create an application by creating a cache manifest file. cache. Local cache files required for applicationUsage:
①Configure manifest fileOn the page:
<!DOCTYPE HTML> <html manifest="demo.appcache"> ... </html>
Manifest files:
Manifest files are simple text files that tell the browser what is cached (and what is not cached). Manifest files can be divided into three sections: ①CACHE MANIFEST - Files listed under this heading will be cached after the first download
②NETWORK - Files listed under this heading require a connection to the server and will not be cached
③FALLBACK - Files listed under this heading Specifies the fallback page when the page cannot be accessed (such as the 404 page)
Full demo:
CACHE MANIFEST # 2016-07-24 v1.0.0 /theme.css /main.js NETWORK: login.jsp FALLBACK: /html/ /offline.html
On the server: The manifest file needs to be configured The correct MIME-type, which is "text/cache-manifest".
<mime-mapping>
<extension>manifest</extension>
<mime-type>text/cache-manifest</mime-type>
</mime-mapping>
Commonly used API:
The core is the applicationCache object, which has a status attribute indicating the current status of the application cache. : 0 (UNCACHED) : No cache, that is, there is no application cache related to the page 1 (IDLE) : Idle, that is, the application cache has not been updated 2 ( CHECKING): Checking, that is, the description file is being downloaded and checking for updates 3 (DOWNLOADING): Downloading, that is, the application cache is downloading the resources specified in the description file 4 (UPDATEREADY): The update is completed and all resources have been downloaded5 (IDLE): Abandoned, that is, the application cache description file no longer exists, so the page can no longer access the application cacheRelated Events:
Indicates changes in the application cache status: checking: Triggered when the browser looks for updates for the application cache error: When checking for updates or downloading Triggered when an error is sent during the resource noupdate: Triggered when checking the description file and finding that the file has no changes downloading: Triggered when starting to download application cache resources progress: In the file Triggered by continuous downloading during the process of downloading the application cacheupdateready: Triggered when the new application cache on the page has been downloadedcached: Triggered when the application cache is fully availableApplication Cache’s three advantages:
① Offline browsing② Improve page loading speed③ Reduce server pressureNotes:
1. Browsers may have different capacity limits for cached data (the limit set by some browsers is 5MB per site)
2 . If the manifest file or one of the files listed internally cannot be downloaded normally, the entire update process will be regarded as a failure, and the browser will continue to use the old cache
3. The HTML that references the manifest must have the same origin as the manifest file and be in the same location. Under a domain
4. The browser will automatically cache the HTML file that references the manifest file. This means that if the HTML content is changed, the version needs to be updated to be updated.
5. The CACHE in the manifest file has nothing to do with the position order of NETWORK and FALLBACK. If it is an implicit declaration, it needs to be at the front.
6. The resources in FALLBACK must have the same origin as the manifest file
7. Update After completing the version, you must refresh it once before starting the new version (the page will be refreshed once), and you need to add a listening version event.
8. Even if the manifest attribute is not set for other pages in the site, the requested resource will be accessed from the cache if it is in the cache
9. When the manifest file changes, the resource request itself will trigger an update
The difference between offline caching and traditional browser caching:
1. Offline caching is for the entire application, and the browser cache is a single file
2. Offline caching is broken You can still open the page even if you are online, but the browser caching is not working
3. Offline caching can actively notify the browser to update resources
Related recommendations: "html video tutorial"
The above is the detailed content of What types of storage methods are there in html5?. For more information, please follow other related articles on the PHP Chinese website!
html5的div一行可以放两个吗Apr 25, 2022 pm 05:32 PMhtml5的div元素默认一行不可以放两个。div是一个块级元素，一个元素会独占一行，两个div默认无法在同一行显示；但可以通过给div元素添加“display：inline;”样式，将其转为行内元素，就可以实现多个div在同一行显示了。
html5中列表和表格的区别是什么Apr 28, 2022 pm 01:58 PMhtml5中列表和表格的区别：1、表格主要是用于显示数据的，而列表主要是用于给数据进行布局；2、表格是使用table标签配合tr、td、th等标签进行定义的，列表是利用li标签配合ol、ul等标签进行定义的。
html5怎么让头和尾固定不动Apr 25, 2022 pm 02:30 PM固定方法：1、使用header标签定义文档头部内容，并添加“position:fixed;top:0;”样式让其固定不动；2、使用footer标签定义尾部内容，并添加“position: fixed;bottom: 0;”样式让其固定不动。
HTML5中画布标签是什么May 18, 2022 pm 04:55 PMHTML5中画布标签是“<canvas>”。canvas标签用于图形的绘制，它只是一个矩形的图形容器，绘制图形必须通过脚本（通常是JavaScript）来完成；开发者可利用多种js方法来在canvas中绘制路径、盒、圆、字符以及添加图像等。
html5中不支持的标签有哪些Mar 17, 2022 pm 05:43 PMhtml5中不支持的标签有：1、acronym，用于定义首字母缩写，可用abbr替代；2、basefont，可利用css样式替代；3、applet，可用object替代；4、dir，定义目录列表，可用ul替代；5、big，定义大号文本等等。
html5废弃了哪个列表标签Jun 01, 2022 pm 06:32 PMhtml5废弃了dir列表标签。dir标签被用来定义目录列表，一般和li标签配合使用，在dir标签对中通过li标签来设置列表项，语法“<dir><li>列表项值</li>...</dir>”。HTML5已经不支持dir，可使用ul标签取代。
Html5怎么取消td边框May 18, 2022 pm 06:57 PM3种取消方法：1、给td元素添加“border:none”无边框样式即可，语法“td{border:none}”。2、给td元素添加“border:0”样式，语法“td{border:0;}”，将td边框的宽度设置为0即可。3、给td元素添加“border:transparent”样式，语法“td{border:transparent;}”，将td边框的颜色设置为透明即可。
html5是什么意思Apr 26, 2021 pm 03:02 PMhtml5是指超文本标记语言（HTML）的第五次重大修改，即第5代HTML。HTML5是Web中核心语言HTML的规范，用户使用任何手段进行网页浏览时看到的内容原本都是HTML格式的，在浏览器中通过一些技术处理将其转换成为了可识别的信息。HTML5由不同的技术构成，其在互联网中得到了非常广泛的应用，提供更多增强网络应用的标准机。
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
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.
Atom editor mac version download
The most popular open source editor
mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.
