This was once a service to aid webmasters with SEO, to claim a website you had to add content to your HTML. While Alexa still provides this service as a subscription, the use of the META tag is no longer required as support was dropped in May 2016!
<meta name="alexaVerifyID" content="your-verification-id-here" />
<a href="..." ping="https://example.com/pingreporter">Example link</a>
The download attribute allows for the downloaded filename to be specified to be something different than the name in the url.
This is available only on the
A tag when an
href attribute is already specified and works similarly to setting the header as:
Content-Disposition: attachment; filename="filename.pdf"
NOTE: this is not currently available in IE, Edge(prior to 13) or IOS Safari.
Silverlight was a browser extension that was backed by Microsoft’s .NET product on many platforms, it provided media capabilities similar to Macromedia/Adobe Flash. Similar to Flash, it has had it’s own share of security problems over the years.
Introduced in 2007 and currently in a deprecated state. Once supported on Windows XP (IE6) to Windows 10 (IE11), MacOS and Ubuntu. Now only supported in MSIE. Edge never provided support. Modern versions of Chrome, Firefox, Safari, and Opera no longer support.
HTML Markup example:
<object data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="100%" height="100%">
<param name="source" value="MySilverLightControl.xap"/>
This practice is now obsolete, and often problematic as there are very few of those browsers in use today – primarily only for testing of legacy functionality.
Example of old approach
// some script
NOTE: for XHTML or XML documents, the use of a CDATA style comment is still required.
The use of
In most cases,
document.write() can be replaced by inserting
Google has recently changed the default behavior, such that when on a slow (currently 2G) connection, but discussions have also leaned toward including any slow connection.
As such, right now, the following will occur on slow (2G) connections:
- Chrome 53+ (warning displayed in debugger console)
- Chrome 55+ (blocked – code will not execute, warning message will appear in debugger console)
For users on slow connections, such as 2G, external scripts dynamically injected via document.write() can delay the display of main page content for tens of seconds, or cause pages to either fail to load or take so long that the user just gives up. Based on instrumentation in Chrome, we’ve learned that pages featuring third-party scripts inserted via document.write() are typically twice as slow to load than other pages on 2G.
My advice – remove all use of document.write() for required content in your code now, as your users MAY NOT see that content if you do not.
You might be tempted to use the full capabilities of your browser to do things such as font-smoothing, but it’s not a good idea as it is often overused and the Browser/OS will generally do it’s best.
Both Firefox and Safari have support of this CSS attribute as follows:
NOTE: If you’re using something like Glyphicons (included with Bootstrap) you might have some use for this because of the way that fonts are used for icons.
Once in a while, the web development community reintroduces old ideas in a new way. Years ago, there was a concept called ECML (E-Commerce Markup Language) that added an HTML attribute to identify values in a FORM that could be auto-filled from a users “virtual wallet”. Sadly, while it was implemented on a variety of websites (mine included), it was not widely supported and disappeared.
The concept has been reintroduced as values in the ‘autocomplete’ attribute in HTML5. Traditionally this attribute was only used to prevent auto-filling of values, now it can identify which values it is related to for pre-fill.
The usual payment, address and demographic fields (and variations of each) are supported.
^<input type="text" name="ccnum" autocomplete="cc-number" value="" />
Link prefetching is used to identify a resource that might be required by the next navigation, and that the user agent SHOULD fetch, such that the user agent can deliver a faster response once the resource is requested in the future.
<link rel="prefetch" href="http://www.example.com/images/sprite.png" />
<link rel="prefetch" href="/images/sprite.png" />
- MSIE 11+/Edge
- Firefox 3.5+ (for HTTPS)
In addition to dns-prefetch, you can take browser performance one step further by actually creating a new connection to a resource.
By initiating an early connection, which includes the DNS lookup, TCP handshake, and optional TLS negotiation, you allow the user agent to mask the high latency costs of establishing a connection.
- Firefox 39+ (Firefox 41 for crossorigin)
- Chrome 46+
<link rel="preconnect" href="//example.com" />
<link rel="preconnect" href="//cdn.example.com" crossorigin />