function getElementAllOfMethod() {
var myTab = document.getElementById('my_tab');
alert('myTab---->' + myTab.value);
var myTab1 = document.myForm.my_tab;
alert('myTab1---->' + myTab1.value);
var myTab2 = document.forms.myForm.my_tab;
alert('myTab2---->' + myTab2.value);
var myTab3 = document.forms[0].my_tab;
alert('myTab3---->' + myTab3.value);
var myTab4 = document.getElementsByTagName("INPUT").my_tab;
alert('myTab4---->' + myTab4.value);
var myTab5 = document.getElementsByTagName("INPUT")[1];
alert('myTab5---->' + myTab4.value);
}