Cutting the mustard

cuttingthemustard1.js

// From Christian Heillman
// http://www.slideshare.net/cheilmann/jsday-48092671
// http://justmarkup.com/log/2015/02/26/cut-the-mustard-revisited/

if ('querySelector' in document &&
    'localStorage' in window &&
    'addEventListener' in window) {
  // Modern browser. Let's add JavaScript functionality
  
}

cuttingthemustard2.js

// Jake Archibald
// A nice way to prevent your JS running in IE<10 and Android Webkit
// http://caniuse.com/#feat=pagevisibility
if (!('visibilityState' in document)) {
    return;
}

cuttingthemustard3.js

// extending the baseline
// Christian Heilmann
if ('visibilityState' in document) {
    // Modern browser. Let's load JavaScript
    if ('serviceWorker' in navigator) {
        // Let's add offline support
        navigator.serviceworker.register('sw.js', {
           scope: './' 
        });
    } 
}