Read Multiple lines of Text field value using JQuery

To read a value of multiple lines of text from a Edit Form or New Form. Assume Comments is the field name

<script  language="javascript" type="text/javascript" >
function PreSaveAction()
{

   var Comments = getTagFromIdentifierAndTitle("textarea","TextField","Comments");  

   var CommentsText = RTE_GetEditorDocument(Comments.id);
   var CommentsTextValue = CommentsText .body.innerText;

}

function getTagFromIdentifierAndTitle(tagName, identifier, title) 

{  

    var len = identifier.length;  

    var tags = document.getElementsByTagName(tagName);  

    for (var i=0; i < tags.length; i++)

    {  

        var tempString = tags[i].id;  

        if (tags[i].title == title && (identifier == "" || tempString.indexOf(identifier) == tempString.length - len))

        {  

            return tags[i];  

        }  

    }  

    return null;  

} 

</script>

Additionally, use the following code to read the selected value of a drop down.

var val =  $("select[title='ChoiceFieldName']").val();