Button-select all check boxes

1 ..................

<SCRIPT>

Function sel ()

{

O = Document. getelementsbyname ("chkbox ")

For (I = 0; I <O. length; I ++)

O [I]. Checked = event. srcelement. Checked

}

</SCRIPT>

<Input type = "checkbox" onclick = 'sel () '> labeling <br>

<Input type = "checkbox" name = "chkbox"> <input type = "checkbox" name = "chkbox"> <input type = "checkbox" name = "chkbox">

2 ...................

<Input type = 'checkbox' name = 'chk1 'Id = 'chk _ fun' value = '1'>

<Input type = 'checkbox' name = 'chk2' id = 'chk _ fun 'value = '1'>

<Input type = 'checkbox' name = 'chk3 'Id = 'chk _ fun' value = '1'>

<Input type = 'checkbox' name = 'chk4 'Id = 'chk _ fun' value = '1'>

<Script language = "JavaScript">

<! -- Begin

VaR checkflag = "false ";

Function check (field ){

If (checkflag = "false "){

For (I = 0; I <field. length; I ++ ){

Field [I]. Checked = true ;}

Checkflag = "true ";

Return "cancel all selections ";}

Else {

For (I = 0; I <field. length; I ++ ){

Field [I]. Checked = false ;}

Checkflag = "false ";

Return "select all ";}

}

// End -->

</SCRIPT>

<Input type = button value = "select all" onclick = "This. value = check (document. All. chk_fun)">