Comprehensive JS checkbox for selecting all, deselecting all, and deleting function codes_javascript skills

function checkAll()
{
var code_Values = document.all['code_Value'];
if(code_Values.length){
for(var i=0;i{
code_Values[i].checked = true;
}
}else{
code_Values.checked = true;
}
}
function uncheckAll()
{
var code_Values = document.all['code_Value'];
if(code_Values.length){
for(var i=0;i{
code_Values[i].checked = false;
}
}else{
code_Values.checked = false;
}
}
function multipleDelete()
{
var num = 0;
var code_Values = document.all['code_Value'];
if(code_Values.length){
for(var i=0;i{
if(code_Values[i].checked == true)
{
num ;
}
}
}else{
if(code_Values.checked == true){
num ;
}
}
if(num == 0){
alert('Please select delete item');
}
if(num >0){
document.BuCodeSearch.action = '<%=EusUtil.getPage("lookup.generic.bucode.delete.s")%>';
document.BuCodeSearch.submit();
}
}

function checkAll()
{
var code_Values = document.getElementsByTagName("input");
for(i = 0;i < code_Values.length;i ){
if(code_Values[i].type == "checkbox")
{
code_Values[i].checked = true;
}
}
}
function uncheckAll()
{
var code_Values = document.getElementsByTagName("input");
for(i = 0;i < code_Values.length;i ){
if(code_Values[i].type == "checkbox")
{
code_Values[i].checked = false;
}
}
}
function multipleDelete()
{
if (document.BuCodeSearch.elements["code_Value"])
{
var num = 0;
var fm = document.BuCodeSearch;
if (document.BuCodeSearch.elements["code_Value"])
{
var elm = document.BuCodeSearch.elements["code_Value"];
var ename = "code_Value";
if (elm.length) {
var len = fm.elements[ename].length;
for (var i = 0; i< len; i ) {
var e = fm.elements[ename][i];
if (e.checked == true){
num ;
}
}
} else {
if (elm.checked == true ) {
num ;
}
}
if (num > 0 )
{
document.BuCodeSearch.action = '<%=EusUtil.getPage("lookup.generic.bucode.delete.s")%>';
document.BuCodeSearch.submit();
}
}
}
}