Comprehensive JScheckbox selection, cancellation of all selections, and deletion of function code _ javascript skills

Today, the code for controlling all checkbox selection, canceling all selection, and deleting functions in JS is pasted .. See the following two implementation methods:
JS checkbox Method 1:

The Code is as follows:

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 ();
}
}
Script

JS checkbox Method 2:

The Code is as follows:

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 ();
}
}
}
}

Code_Value is the name of the checkbox form, and BuCodeSearch is the form name.

The Code is as follows: