Why prompt Cannot read property 'getElementsByClassName' of undefined


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var index = 0, 

timer = null,
banner= byId("banner").getElementsByTagName("div"),
dots  = byId("dots").getElementsByTagName("span"),
len   = banner.length,
prev  = byId("prev"),
next  = byId("next"),
menu  = byId("menu-content"),
subMenu   = byId("sub-menu"),
innerBox  = subMenu.getElementsByClassName("inner-box"),
menuItems = menu.getElementsByClassName("menu-item");
Html javascript
Aug.31,2021

whether there is no domReady?

what is byId

your menu-content is obtained through id, and there is no id menu-content in dom. It seems that there are several others you have also got wrong

happily tell you that submenun did not get, it is undefined

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b36d02-2c027.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b36d02-2c027.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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