nl_tokens: doubletap detection
pl_tokens: function touchstart ( ) { start . apply ( this , arguments ) ; var touches = d3_behavior_zoomTouchup ( ) , touch , now = Date . now ( ) ; if ( ( touches . length === 1 ) && ( now - d3_behavior_zoomLast < 300 ) ) { d3_behavior_zoomTo ( 1 + Math . floor ( xyz [ 2 ] ) , touch = touches [ 0 ] , d3_behavior_zoomLocations [ touch . identifier ] ) ; } d3_behavior_zoomLast = <mask> ; }