// If nothing selected, select all.
var currentSelection = getSelection();

// A find'n replace using regular expression
// (in selected range only).
currentSelection.Replace("^\\s*$\\n", "", eeReplaceSelOnly | eeReplaceAll | eeFindReplaceRegExp);

// earase search keyword highlighting.
document.HighlightFind = false;

// If nothing selected, select all.
var currentSelection = getSelection();

// A find'n replace using regular expression 
// (in selected range only).
currentSelection.Replace("\\n", "\\n\\n", eeReplaceSelOnly | eeReplaceAll | eeFindReplaceRegExp);

// earase search keyword highlighting.
document.HighlightFind = false;