Help block display effect has not been defined

< html >

< head >

< meta charset= "gbk" / >

< title > shoppingCar < / title >

< style >

< H1 > content ul {< / H1 >

display:flex;
flex-direction:row;
justify-content:center;

list-style:none;
height:36px;

}

< H1 > content ul li {< / H1 >

line-height:36px;
width:100px;
background-color:rgb (63,117,160);
background-position:0-36px;
}

< H1 > content ul li < / H1 >

cursor:pointer;

}

< H1 > content. Sub {< / H1 >

width:350px;
font-size:15px;
background-color:grey;
text-align:center;
display:none;

}
.sub span {
margin-right:5px;

}

< / style >
< / head >

< body >

< div id="content" >

  • Home of webmasters

  • Industry Information < div class="sub" style="display:none;" >

    Industry Trends acquisition financing

    Portal Trends search engine

    < / div >

  • webmaster online < div class="sub" style="display:none;" >

    webmaster reports recommendation

    span > webmaster gathering War commander meeting

    < / div >

  • website operation < div class="sub"style="display:none;">

    site building experience Planning profit

    span > search optimization website promotion

    < / div >

  • Design online < div class="sub" style="display:none;" >

    recommendation WEB Standard

    span > Video processing Design activity

    < / div >

  • Network programming < div class="sub" style="display:none;" >

    ASP programming PHP programming

    .NET programming XML programming

    < / div >
  • Server < div class="sub" style="display:none;" >

    WEB Server ftp Server

    DNS Server linux Server

    < / div >

< / div >

< script type= "text/javascript" >

var get= {

byId:function (elem) {

return document.getElementById(elem);

},
byClass:function (sClass,ele) {

var cla=[]; 
var reClass = new RegExp("(^| )" + sClass + "( |$)");
var allClass=this.byTagName("*",ele);
for(var i=0;i<allClass.length;iPP)reClass.test(allClass[i].className)&&cla.push(allClass[i])



return cla

},
byTagName:function (obj,ele) {

return (document | | obj) .getElementsByTagName (ele);

}
}; / / Encapsulation

window.onload=init;
function init () {
var content=get.byId ("content");

var nav=get.byTagName (content,"li");
console.log (nav);
var cls=get.byClass ("sub",content);
console.log (cls);
var timer=null;
sub1=null;
var iTuno;
for (iSomei < nav.length;iPP) {
navi] .onMouseover = function () {

for (iBoth I < cls.length;iPP) {

cls[i].style.display="none";
}

var sub1=null;
var timer=null;
sub1=get.byClass ("sub",this);
console.log (sub1);
console.log (timer);
sub1.style.display= "block";

content.offsetWidth-this.offsetLeft > cls.offsetWidth?

cls.style.left=this.offsetLeft+"px":cls.style.right=0;

sub.onmouseover=function (event) {
(event | | window.event) .cancleBubble = true;
clearTimeout (timer);

}

}

}

}

< / script >
< / body >

< / html >

sub1.style.display= "block"; this step always goes wrong and asks for advice

Mar.04,2022

look at the code of lz. get.byClass calls

.
for (const node of get.byClass('sub',this)) {
    node.style.display = 'block';
}
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