text: /**
   * Support for swipe and tap on touch devices
   *
   * This plugin implements navigation for plugin devices, via swiping left/right,
   * or tapping on the left/right edges of the screen.
   *
   *
   *
   * Copyright 2015: Andrew Dunai (@and3rson)
   * Modified to a plugin, 2016: Henrik Ingo (@henrikingo)
   *
   * MIT License
   */
  /* global document, window */
  ( function( document, window ) {
      "use strict";
  
      // Touch handler to detect swiping left and right based on window size.
      // If the difference in X change is bigger than 1/20 of the screen width,
      // we simply call an appropriate API function to complete the transition.
      var startX = 0;
      var lastX = 0;
      var lastDX = 0;
      var threshold = window.innerWidth / 20;
  
      document.addEventListener( "touchstart", function( event ) {
          lastX = startX = event.touches[ 0 ].clientX;
      } );
  
      document.addEventListener( "touchmove", function( event ) {
           var x = event.touches[ 0 ].clientX;
           var diff = x - startX;
  
           // To be used in touchend
           lastDX = lastX - x;
           lastX = x;
  
           // window.impress().swipe( diff / window.innerWidth );
       } );
  
       document.addEventListener( "touchend", function() {
           var totalDiff = lastX - startX;
           if ( Math.abs( totalDiff ) > window.innerWidth / 5 && ( totalDiff * lastDX ) <= 0 ) {
               if ( totalDiff > window.innerWidth / 5 && lastDX <= 0 ) {
                   window.impress().prev();
               } else if ( totalDiff < -window.innerWidth / 5 && lastDX >= 0 ) {
                   window.impress().next();
               }
           } else if ( Math.abs( lastDX ) > threshold ) {
               if ( lastDX < -threshold ) {
                   window.impress().prev();
               } else if ( lastDX > threshold ) {
                   window.impress().next();
               }
           } else {
  
               // No movement - move (back) to the current slide
               window.impress().goto( document.querySelector( "#impress .step.active" ) );
           }
       } );
  
       document.addEventListener( "touchcancel", function() {
  
               // Move (back) to the current slide
               window.impress().goto( document.querySelector( "#impress .step.active" ) );
       } );
  
  } )( document, window );
  