JS - List of devices and his viewports to use with grunt-screenshot, snippet proudly "stolen" from yeoman generator-mobile.

devices-viewport.js

var devices = [
  {
    name: 'G1',
    width: 320,
    height: 480,
    density: 1
  }, {
    name: 'Nexus S',
    width: 480,
    height: 800,
    density: 1.5
  }, {
    name: 'Nexus 4',
    width: 768,
    height: 1280,
    density: 2
  }, {
    name: 'Nexus 7 Orig.',
    width: 800,
    height: 1280,
    density: 1.33
  }, {
    name: 'Nexus 7 2.0',
    width: 1200,
    height: 1920,
    density: 2
  }, {
    name: 'Xoom',
    width: 800,
    height: 1280,
    density: 1
  }, {
    name: 'Nexus 10',
    width: 1600,
    height: 2560,
    density: 2
  }, {
    name: 'iPhone 3GS',
    width: 320,
    height: 480,
    density: 1
  }, {
    name: 'iPhone 4 / 4S',
    width: 640,
    height: 960,
    density: 2
  }, {
    name: 'iPhone 5',
    width: 640,
    height: 1136,
    density: 2
  }, {
    name: 'iPad 1 & 2',
    width: 768,
    height: 1024,
    density: 1
  }, {
    name: 'iPad 3 & 4',
    width: 1536,
    height: 2048,
    density: 2
  }
];

var skipList = {};
this.viewports = '';
for(var i = 0; i < devices.length; i++) {
  var device = devices[i];
  var width = Math.ceil(device.width / device.density);
  var height = Math.ceil(device.height / device.density);

  // Only width matters since screenshot is of full height
  var identifier = width;// +'x'+height;
  if(typeof skipList[identifier] !== 'undefined') {
    continue;
  }

  skipList[identifier] = {};

  if(i !== 0) {
    this.viewports += ',';
  }

  this.viewports += '\''+width+'x'+height+'\',';
  this.viewports += '\''+height+'x'+width+'\'';
}