Modern browsers include different rendering modes to support both standard compliant web pages and web pages designed for older browsers. Among them, standards mode i. The browser automatically switches to the appropriate rendering mode to correctly display the document type specified by the DOCTYPE declaration.
In theory, this should be a very intuitive switch. In this way, the browser can display the standard documents correctly without abandoning the old-fashioned web pages. Therefore, the existence of XML Prolog will make ie, opera and safari enter quirks mode. If the URL is missing, or if a relative path rather than a fully qualified Internet address is specified, most browsers will enter quirks mode, regardless of the mode specified in the DOCTYPE declaration.
DOCTYPE switching may be an effective way to let the browser enter the correct rendering mode and display the web page correctly, provided that you notice the inconsistency of various browsers and can actively avoid various problems.
We usually ignore this point when we make pages including me, who are usually lazy not to write and use the browser default. With the arrival of the current upsurge of web page coding standardization, it is necessary for us to understand this detail, which will be useful. As the saying goes, there is no square without rules.
Each DTD includes a series of tags, attributes and properties, which are used to tag the content of Web documents; In addition, there are rules that specify which tags can appear in which other tags. Browsers are more tolerant than checkers to the problem of inconsistent tags. In this case, the browser will use the built-in DTD to try to display the tag you specified. However, because most web documents need to follow an internationally recognized web standard published by W3C, those documents usually contain one of the following standard DOCTYPE statements:.
HTML 4. XHTML 1. After deletion, the browser will use the default DTD of. The codes of other standard sites such as k10k. Net are as follows:. Because this kind of DTD also allows us to use the identification, elements and attributes of the presentation layer, and it is easier to pass the W3C code verification. The purpose of our transition is to realize the separation of data and representation.
For example: mannequins change clothes. Models are like data, while clothes are forms of expression. Raynos, what are you talking about? My point was that it's 2 years older than the HTML5 change on doctype. Thus, it isn't really reliable since it doesn't make reference to the discussion.
They have plenty of pages on that site that are well beyond out of date. So yes, I am saying that when the spec is superceeded. Show 2 more comments. Stuart Burrows Stuart Burrows George Cummins George Cummins From W3Schools. Ken Pespisa Ken Pespisa The doctype declaration should be the very first thing in an HTML document, before the tag.
The Overflow Blog. Does ES6 make JavaScript frameworks obsolete? Podcast Do polyglots have an edge when it comes to mastering programming Featured on Meta. Now live: A fully responsive profile. Visit chat. Linked See more linked questions. Related Hot Network Questions. Stack Overflow works best with JavaScript enabled. Accept all cookies Customize settings. HTML is an old language that has been revised and extended several times to make it cleaner, more efficient, standardised and feature rich.
Whenever any software evolves, it leaves behind a trail of backwards compatibility issues. But with the Internet containing millions of published pages, all containing instances of old techniques, the question must be asked… How do you keep these pages still working, whilst moving the language forward?
Newer web browsers are equipped to handle several versions of HTML. These include HTML 2. If you do not wish to read the full contents of this article, if there is one thing I can teach you This will ensure that your browser will use the latest browser engine to render your pages without as many compatibility issues.
In addition to these versions, there are also two rendering modes. These are quirks mode and strict mode. In the past, the implementations of CSS across browsers were not as standardised. Quirks mode refers to a mode where browsers emulate rendering bugs from older browser versions to ensure backwards compatibility. For example, given the CSS style: height: px; padding-top: 10px" , does the height of px include or exclude the value of the 10px padding?
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