js的选择与反选择的一个实例

<HTML>
<HEAD>
<TITLE> TEST THE PROGRAM ...</TITLE>
<META HTTP-EQUIV=Content-Type CONTENT="text/html; charset=gb2312">
<META HTTP-EQUIV="expires" CONTENT="0">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<STYLE type="text/css">
BODY,TD,INPUT,TEXTAREA {font-family: "Verdana", "Arial","新宋体", "宋体";font-size:9pt;}
</STYLE>
<SCRIPT Language="JavaScript">
<!--
var put=document.all.tags("input");

function selall() {
for (i=0;i<put.length;i++) {
if (put[i].type=="checkbox") put[i].checked=true;
}

}

function selfx() {
for (i=0;i<put.length;i++) {
if (put[i].type=="checkbox") put[i].checked=(put[i].checked)?false:true;
}
}

// -->
</SCRIPT>
</HEAD>

<BODY SCROLL="AUTO" bgcolor="#FFFFFF">
<INPUT TYPE="BUTTON" VALUE=" 选择所有 " onclick="selall()">
<INPUT TYPE="BUTTON" VALUE=" 反择 " onclick="selfx()">
<input type="checkbox" name="chb1" value="" >
<input type="checkbox" name="chb1" value="" >
<input type="checkbox" name="chb1" value="" >
<input type="checkbox" name="chb1" value="" checked>
<input type="checkbox" name="chb1" value="" checked>
<input type="checkbox" name="chb1" value="" checked>

</BODY>
</HTML>