/* Property */
/* Scan pages in 200 DPI */
DWObject.Resolution = 200;

// Method
  
///
<summary> /// Rotates the image of a specified index in buffer by a specified angle.
  /// </summary>
///
<param name="sImageIndex" type="short">
specifies the index of image in buffer. The index is 0-based.
</param>
///
<param name="fAngle" type="float">
specifies the angle.
///
<param name="bKeepSize" type="bool">
specifies whether to keep the original size
///
<returns type="bool"></returns>
DWObject.Rotate(0, 45, false); // rotate the 1st image in the buffer by 45 degrees

<script type="text/javascript">
Dynamsoft.WebTwainEnv.RegisterEvent('OnWebTwainReady', Dynamsoft_OnReady);
var DWObject; 
/* OnWebTwainReady event fires as soon as Dynamic Web TWAIN is initialized and ready to be used. It is the best place to add event listeners */
function Dynamsoft_OnReady() {
   DWObject = Dynamsoft.WebTwainEnv.GetWebTwain('dwtcontrolContainer');
   DWObject.RegisterEvent("OnPostTransfer", Dynamsoft_OnPostTransfer);
}
function Dynamsoft_OnPostTransfer() { 
   /* This event OnPostTransfer will be triggered after a transfer ends. */
   /* your code goes here*/
}
</script> 

<script type="text/javascript">
Dynamsoft.WebTwainEnv.RegisterEvent('OnWebTwainReady', Dynamsoft_OnReady);
var DWObject; 
function Dynamsoft_OnReady() {
   DWObject = Dynamsoft.WebTwainEnv.GetWebTwain('dwtcontrolContainer');
   DWObject.RegisterEvent("OnPostTransfer", function() { 
    /* your code goes here*/
   });
}
</script>

/* sImageIndex is the index of the image you clicked on*/
OnMouseClick(short sImageIndex) 

function DynamicWebTwain_OnMouseClick(index) {
    CurrentImage.value = index + 1;
}

DWObject.RegisterEvent("OnPostTransfer", function(index) { 
    CurrentImage.value = index + 1;
});

<script type="text/javascript">
Dynamsoft.WebTwainEnv.RegisterEvent('OnWebTwainReady', Dynamsoft_OnReady);
var DWObject; 
function Dynamsoft_OnReady() {
   DWObject = Dynamsoft.WebTwainEnv.GetWebTwain('dwtcontrolContainer');
}
</script>

<script type="text/javascript">
   Dynamsoft.WebTwainEnv.RegisterEvent('OnWebTwainReady', function() {
     DWObject = Dynamsoft.WebTwainEnv.GetWebTwain('dwtcontrolContainer');
   });
</script>