Facebook open-sourced React Native this week, and the pitch is bold: write native mobile apps using JavaScript and React. Not hybrid apps like PhoneGap—actual native apps with native performance and native UI components.
This is ambitious. The question is whether JavaScript's "write once, run anywhere" promise finally delivers or disappoints again.
Responsive web design has solved many problems related to building websites that work across devices—fluid grids adapt our layouts, media queries adjust our styles, and flexible images scale to fit their containers. But there's one aspect of responsive design that remains frustratingly unsolved: the responsive images problem.
The issue is straightforward: responsive websites need images that adapt not just visually but also technically. When you set max-width: 100% on an image, it scales down beautifully on mobile devices, but there's a hidden problem—that mobile device still downloaded the full-size desktop image. A user on a smartphone with a 320-pixel-wide screen doesn't need your 1200-pixel-wide hero image, yet they're downloading it anyway, wasting bandwidth and slowing down page load times.
The mobile web is here. iPhones, Android phones, iPads – users access the web from dozens of devices with different screen sizes. The traditional approach of building separate mobile sites is becoming unsustainable.
Enter responsive web design, a term coined by Ethan Marcotte in his recent article on A List Apart. The idea is simple but powerful: use CSS to adapt your site's layout to the viewing device. One site, one codebase, works everywhere.