I have written some js in recent projects, but my level needs to be improved_javascript skills

Copy code The code is as follows:

function ResumeError() {
return true;
}
window.onerror = ResumeError;

function showdd(obj){
var dds = document.getElementById(obj).getElementsByTagName("dd");
var len = dds.length ;
if(dds[0].style.display == "none"){
//This operation is to expand the menu, and you need to determine whether the item exists in the cookie
//1. If yes, delete
//2. None, no operation is performed
changeshowmenu(obj);
for(var i = 0; i < len;i ){
dds[i].style.display = "";
}
}else{
//This operation is a hidden menu. You need to determine whether the item exists in the cookie:
//1. If yes, do not perform the operation
// 2. If none, add it at the end
changehidemenu(obj);
for(var i = 0; i < len;i ){
dds[i].style.display = "none ";
}
}
}

function changeshowmenu(obj){
var temp = getcookie("openid");
if(temp.indexOf(obj) != "-1"){
temp = temp.replace(obj ",","")
addcookie("openid",temp,24);
}
}

function changehidemenu(obj){
var temp = getcookie("openid");
if(temp.indexOf(obj) == "-1"){
addcookie("openid", temp obj ",",24);
}
}


function getcookie(sName) {//Get cookie
var aCookie = document.cookie.split("; ");
for (var j=0; j < aCookie.length; j ){
var aCrumb = aCookie[j].split("=");
if (sName == aCrumb [0])
return aCrumb[1];
}
return null;
}

function addcookie(objName,objValue,objHours){//Add cookie
var str = objName "=" objValue;
if(objHours > 0){//When it is 0, no expiration time is set, and the cookie automatically disappears when the browser is closed
var date = new Date();
var ms = objHours*3600*1000;
date.setTime(date.getTime() ms);
str = "; expires=" date.toGMTString();
}
document .cookie = str;
}

//According to a comma-separated string, which parts of the initialization menu need to be hidden
function initmenu(obj){
var arrmenu = obj.split( ",");
for(var i = 0; i < arrmenu.length;i ){
var dds = document.getElementById(arrmenu[i]).getElementsByTagName("dd");
for(var j = 0;j < dds.length;j ){
dds[j].style.display = "none";
}
}
}

function $(obj){
return document.getElementById(obj);
}

function delIt(){
var cbxBool = 0;
for(var i = 0;i < cbxArray.length;i ){
var obj = $(cbxArray[i]);
if(obj.checked == true){
cbxBool = 1;
break ;
}
}

if(cbxBool == 1){
var result = confirm("The operation cannot be resumed, are you sure about the current operation? ");
if(result){
return true;
}
}else{
alert("You have not selected the item yet");
return false;
}
return false;

}
window.onload = function(){
var lendl = document.getElementById("globalLeft").getElementsByTagName("dl").length;
if(getcookie("openid") == null){
addcookie("openid","dl_c,dl_d,dl_e,dl_f,dl_g,dl_h,dl_i,dl_j,",24);
}
initmenu(getcookie("openid"));



var otable = document.getElementById("table");
var trs = otable.getElementsByTagName("tr" );
for(var i = 0;i < trs.length;i ){
trs[i].onmouseover = function(){
this.style.backgroundColor = "#F7F7F7";
}
trs[i].onmouseout = function(){
this.style.backgroundColor = "#FFFFFF";
}
}
}