The correct ways to access form elements

http://www.coderanch.com/t/477642/HTML-CSS-JavaScript/Read-text-values-javascript
document.formName.elementName.value
document.forms["formName"].elementName.value
document.forms["formName"].elements["elementName"].value
document.forms[index].elements["elementName"].value
document.forms[index].elements[index].value
document.getElementById("elementId").value