Javascript Function to determine if where running as a webapp

checkIsWebApp.js

function detectWebApp() {
  var ua          = navigator.userAgent.toLowerCase();
  var isAndroid   = ua.indexOf("android") ]]> -1;
  var isIOS       = ua.match(/(ipad|iphone|ipod)/g);
  var isChrome    = ua.indexOf("chrome") ]]> -1;
  var offset      = new Array();
  var sh          = screen.availHeight;
  var sw          = screen.availWidth;
  var ih          = window.innerHeight;
  var iw          = window.innerWidth;
  var isWebApp    = false;
  var debug       = false; // for now only test for android and iOS, other mobile platforms may be included later
  
  if(isAndroid || isIOS) {    // yes we're on a mobile OS    
    if(isIOS) {        
      if(window.navigator.standalone)  isWebApp = true;    
    } else {        
      // it is not IOS        
      if(isAndroid) {            
        offset[0] = 0;      // <- not all android devices show status header            
        offset[1] = 25;     // <- is android status header            
        offset[2] = 44;     // <- is including error message ssl cert;                                    
                            // documentation says 25dp = status header                                   
                            // , up til now all devices show this in javascript as 25px.                                   
                            // todo check offset for other android devices        
      } else {            
        // for future use, if mobile platform other than iOS or android            
        offset[0] = 0;        
      }        
      
      if(window.orientation==0) {            
        for (var i = 0; i < offset.length; i++) {                
          if(ih == (sh - offset[i])) {                    
            if(debug) alert(window.orientation + ' ' + ih + '==' + sh + ' offset:' + offset[i]);                    
            isWebApp = true;                    
            break;                
          }            
        }        
      } else {            
        if(isAndroid && isChrome) {                
          // chrome on android doesn't switch values of availHeight and availWidth on orientation landscape                
          for (var i = 0; i < offset.length; i++) {                    
            if(ih == (sh - offset[i])) {                        
              if(debug) alert(window.orientation + ' ' + ih + '==' + sh + ' offset:' + offset[i]);                        
              isWebApp = true;                        
              break;                    
            }                
          }            
        } else {                
          for (var i = 0; i < offset.length; i++) {                    
            if(ih == (sw - offset[i])) {                        
              if(debug) alert(window.orientation + ' ' + ih + '==' + sw + ' offset:' + offset[i]);                        
              isWebApp = true;                        
              break;                    
            }                
          }            
        }        
      }    
    }
  
  }
  return isWebApp;
}