<!DOCTYPE HTML Public "-//W3C//DTD XHTML 1.0 transitional//en" "http://www.w3.org/TR/xhtml1/DTD/ Xhtml1-transitional.dtd "><HTMLxmlns= "http://www.w3.org/1999/xhtml"><Head><Metahttp-equiv= "Content-type"content= "text/html; charset=utf-8" /><title>Untitled Document</title></Head><style>#innav{position:relative;}</style><Script>window.onload=function() {Innav=document.getElementById ('Innav'); Innav.style.display='None'; } functionxs () {Innav.style.display='Block'; Innav.style.left="'; } functionYC () {Innav.style.display='None'; }</Script><Body><ulID= ' nav '><Li>Home</Li><Li>Company Profile</Li><Li>Product Show<ulID= ' Innav '><Li>One</Li><Li>Both</Li><Li>Three</Li><Li>Four</Li></ul></Li><Li>Contact Us</Li></ul><Buttononclick= ' xs (); '>Xs</Button><Buttononclick= ' YC (); '>Yc</Button></Body></HTML>
If you want the script to be executed after the Web page has been loaded, JS still wants to write it at the beginning of the page, using the Window.onload=function () {This write function}
There is also the scope of the object, within a function can be shared, including nested,
If it is not inside a function, it needs to be fetched again on the page.
JS Control ul display hidden, object valid range