js tr controls the hiding and display of the tbody below_javascript skills

The core code used is
function $(obj){
return document.getElementById(obj);
}
window.onload = function(){
var table = document.getElementById(" myTable");
//If a click occurs in the table area
table.onclick = function(e){
var e = window.event||e,target = e.srcElement||e .target;

//Get tr
while(target.tagName.toLowerCase() != "tr"){
target = target.parentNode;
}

var i = target.rowIndex;
//Click on a single row of Tr to control the hiding and display of tr 1

if(i%2 == 0){
var nrs = table .rows[i 1].parentNode.style;
nrs.display = nrs.display == "none"?"":"none";
}
}
}

<meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <title>Layer hidden</title> <table border="1" id="myTable"> <tr><td></td></tr> </table>