Some of the most common questions we get here at Rollbar deal with source maps:

• What are source maps and what do they do?
• How can you enable source mapping?
• Why aren't your source maps working properly?

Let's explore Javascript source maps together, starting with the basics.

As web developers, we have two major goals. First, we want a highly performant website. Second, we want that website to be easy to debug and maintain. Unfortunately, these goals are often at odds with one other. If we minimize our JavaScript, we can achieve some of these goals. Minimizing JavaScript reduces the download size, and the smaller the payload for our website users, the better. If we combine our JavaScript files, we can also reduce the number of http requests.

... read the whole story at rollbar.com.

The font-display property defines how font files are loaded and displayed by the browser. It is applied to the @font-face rule which defines custom fonts in a stylesheet.

@font-face { font-family: 'MyWebFont'; /* Define the custom font name */ src: url('myfont.woff2') format('woff2'), url('myfont.woff') format('woff'); /* Define where the font can be downlaoded */ font-display: fallback; /* Define how the browser behaves during download */ }

The font-display property accepts five values:

• auto (default): Allows the browser to use its default method for loading, which is most often similar to the

... read the whole story at css-tricks.com.

A new version of Safari shipped with the release of iOS 10.3 and macOS Sierra 10.12.4. Safari on iOS 10.3 and Safari 10.1 on macOS adds many important web features and improvements from WebKit that we are incredibly excited about.

While this release makes the web platform more capable and powerful, it also makes web development easier, simplifying the ongoing maintenance of your code. We’re excited to see how web developers will translate these improvements into better experiences for users.

Read on for quick look at the features included in this release:

Fetch

Fetch is a modern replacement for XMLHttpRequest

... read the whole story at webkit.org.

HTML5 download Attribute

I tend to get caught up on the JavaScript side of the HTML5 revolution, and can you blame me? HTML5 gaves us awesome "big" stuff like WebSockets, Web Workers, History, Storage and little helpers like the Element classList collection. There are, however, smaller features in HTML5 that we can appreciate; one of those would be the new download attribute. The download attribute allows you to set a separate file download name than the actual link endpoint itself.

The HTML

Place the download attribute on a link...

 <!-- will download as "expenses.pdf" --> <a href="/files/adlafjlxjewfasd89asd8f.pdf" download="expenses.pdf">Download Your Expense Report</a> 

... read the whole story at davidwalsh.name.

CSS Loaders

Collection of HTML and CSS loader animation. Demo and download code (*zip).

Preloader With Anime.js (demo image)

Preloader With Anime.js

HTML/CSS preloader with Anime.js.
Made by Kevin Konrad
February 25, 2017

Jelly Box (demo image)

Jelly Box

Pure CSS jelly box loader.
Made by Fabrizio Bianchi
February 6, 2017

Spring Loader (demo image)

Spring Loader

HTML and CSS spring loader.

... read the whole story at freefrontend.com.

Tomorrow I’m speaking at ImageCon. It’s been over a year since I last gave my talk. As I dusted off my presentation and updated it, it seemed like a good time to assess the state of the responsive images.

To start with, we should acknowledge that we’re in fantastic shape compared to where we were in 2010 when I first wrote about responsive images.

The new responsive images standards are available in all current browsers with the exception of Opera Mini. And if your fallback image is optimized for small screens—which it should be—Opera Mini’s lack of support isn’t a problem.

I still get questions from designers and developers who find different behavior from browser to browser. Some of this is by design. We want

... read the whole story at cloudfour.com.