What are best practices to order elements in <head>?
can use anything in any order? does placing of is important before
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According to W3 should be:
- Meta charset
- Title
- Meta name="descripition"
- Meta name="keywords"
- Stylesheet
- JavaScript Files
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Most browsers don't mind how you order your elements, but you should always specify
charsetfirst.Best practices for IE7+ require that the
charset,X-UA-Compatible, andbasedeclarations occur before anything else in thehead, otherwise the browser starts over and re-parses everything that came before.讨论(0) -
You want your content-type first as this denotes the character encoding, otherwise if it comes later on, some browsers attempt to guess the encoding. (I can't remember the specifics, but I think IE will guess if it doesn't find an encoding in the first 75 characters of the document?)
Most webservers send the encoding in the HTTP headers, but if a user saves your page, the headers aren't saved with it.
I'd put CSS references second so the browser downloads them as soon as possible.
JavaScript I wouldn't put in the head, it should go at the bottom of your pages as downloading them blocks rendering of pages.
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In HTML, the
DOCTYPEmust come first, followed by a single<html>element, which must contain a<head>element containing a<title>element, followed by a<body>element. See the description of the global structure of an HTML document in HTML 4.01 and the HTML5 draft; the actual requirements are mostly the same other than theDOCTYPE, but they are described differently.The actual tags (
<html>,</html>,<head>, etc) are optional; the elements will be created automatically if the tags don't exist.<title>is the only required tag in HTML. The shortest valid HTML 4.01 document (at least, that I could generate) is (needs a<p>because there needs to be something in the<body>to be valid):<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><title></title><p>And the shortest valid HTML5 document:
<!DOCTYPE html><title></title>Note that in XHTML, all tags must be specified explicitly; no elements will be inserted implicitly.
Browsers perform content type sniffing in some circumstances to determine the type of a resource that hasn't been specified using a
Content-TypeHTTP header, and also character encoding sniffing if theContent-Typeheader hasn't been supplied or doesn't include acharset(you should generally try to include these headers, and make sure that they are correct, but there are some circumstances in which you cannot, such as local files not transferred over HTTP). They only sniff a limited number of bytes at the beginning of the document for these purposes, though, so anything that is intended to affect the content sniffing or character encoding sniffing should be near the beginning of the document.For this reason, HTML5 specifies that any
metatag which is used to specify the character set (either<meta http-equiv="Content-type" content="text/html; charset=...">or simply<meta charset=...>) must be within the first 1024 bytes of the file in order to take effect. So, if you are going to include character encoding information within your document, you should put the tag early in the file, possibly even before the<title>element. But recall that this tag is unnecessary if you properly specify aContent-typeheader.In CSS, later style declarations take precedence over earlier ones, all else being equal. So, you should generally put the most generic style sheets that may be overridden earlier, and the more specific style sheets later.
For performance reasons, it can be a good idea to put scripts at the bottom of the page, right before the
</body>, because loading scripts blocks the rendering of the page.Obviously,
<script>tags should be ordered so that scripts that depend on each order have the dependencies loaded first.On the whole, other than the constraints I have already specified, the ordering of tags within
<head>shouldn't matter too much, other than for readability. I tend to like to see the<title>towards the top, and put the other<meta>tags in some sort of logical order.Most of the time, the order you should put things into the body of an HTML document should be the order they should be displayed in, or the order they should be accessed. You can use CSS to rearrange things, but screen readers will generally read things in source order, search indexes will extract things in source order, and so on.
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Adding a few performance suggestions to Brian's answer, highest priority should logically be things that will need to be downloaded, so the browser can start downloading them asap, and things that will affect how the page is presented. So I'd suggest:
- Metas affecting appearance, such as charset (required early by the spec too), viewport, apple-mobile-web-app-capable
- Title near the top so the browser can render it asap and user has a sense something is happening
- Favicon and touch icons
- CSS (at least CSS for above-the-fold; other CSS can be loaded in the footer if you want to get fancy). This step typically blocks everything else from proceeding, which is why I put the previous items above it, as they provide some feedback during the CSS delay.
- Critical scripts (such as user-agent sniffing that may affect layout) which can't be loaded in the footer
- Everything else (e.g. necessary metadata in the form of links and meta tags)
You might also consider inlining whatever CSS and JS is loaded in head, especially if its small and the external script/sheet is unlikely to be cached according to your typical visitor's profile. And if you do inline it, you'll ideally want to compress it.
Last thing: The user has to wait around for head - and any blocking resources it loads - so it's best to put as much as possible in the body or footer.
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This is the template I use, just delete whatever you dont need for a new project.
<!doctype html> <html class="no-js" lang="en"> <head> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta charset="utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title></title> <meta name="description" content=""> <meta name="keywords" content=""> <meta name="author" content=""> <meta name="robots" content="index, follow"> <meta name="mobile-web-app-capable" content="yes"> <meta name="apple-mobile-web-app-capable" content="yes"> <meta name="apple-mobile-web-app-status-bar-style" content="default"> <link rel="stylesheet" href="scss/style.css" /> <!-- http://realfavicongenerator.net/ --> <meta property="fb:page_id" content=""> <meta property="og:title" content=""> <meta property="og:image" content=""> <meta property="og:description" content=""> <meta property="og:url" content=""> <meta property="og:site_name" content=""> <meta property="og:type" content="website"> <meta name="twitter:card" content="summary"> <meta name="twitter:url" content=""> <meta name="twitter:title" content=""> <meta name="twitter:description" content=""> <meta name="twitter:image" content=""> <meta name="twitter:site" content=""> <script src="js/vendor/modernizr.js"></script> </head> <body> </body> </html>讨论(0)
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