Get Value of any SharePoint Control Using JavaScript

You can Get any Form Field Value By Using This JS Function

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;
}

Ex:
getTagFromIdentifierAndTitle('input','TextField', 'Title').value