I want to use javascript to determine the character code of the cursor position and branch conditions.

 document.selection.Collapse();// Unselect if a selection exists
varx = document.selection.GetActivePointX(eePosLogical);
variable = document.selection.GetActivePointY(eePosLogical);
var str = document.GetLine(y);
varch = str.charAt(x-1);
alert(ch);// Rewrite this line