Processing function under onMouseOver_html/css_WEB-ITnose

<div id="channelmenu">	<a href="index.php" target="_self" class="channelmenu_main" id="channelmenu_main_0" onMouseOver="showSubMenu('channelmenu_main','channelmenu_sub',0)">网站首页</a><div id="menuright" style="float:left;height:27px;width:2px;margin-right:5px;background:url(menu/templates/images/channelmenu_diy/li.gif) no-repeat;"></div>	<a href="page/html/company.php" target="_self" class="channelmenu_main" id="channelmenu_main_1" onMouseOver="showSubMenu('channelmenu_main','channelmenu_sub',1)">关于我们</a><div id="menuright" style="float:left;height:27px;width:2px;margin-right:5px;background:url(menu/templates/images/channelmenu_diy/li.gif) no-repeat;"></div>	<a href="news/class/?104.html" target="_self" class="channelmenu_main" id="channelmenu_main_2" onMouseOver="showSubMenu('channelmenu_main','channelmenu_sub',2)">服务领域</a><div id="menuright" style="float:left;height:27px;width:2px;margin-right:5px;background:url(menu/templates/images/channelmenu_diy/li.gif) no-repeat;"></div>	<a href="page/solution/?83.html" target="_self" class="channelmenu_main" id="channelmenu_main_3" onMouseOver="showSubMenu('channelmenu_main','channelmenu_sub',3)">解决方案</a><div id="menuright" style="float:left;height:27px;width:2px;margin-right:5px;background:url(menu/templates/images/channelmenu_diy/li.gif) no-repeat;"></div>	<a href="news/class/?86.html" target="_self" class="channelmenu_main" id="channelmenu_main_4" onMouseOver="showSubMenu('channelmenu_main','channelmenu_sub',4)">新闻动态</a><div id="menuright" style="float:left;height:27px;width:2px;margin-right:5px;background:url(menu/templates/images/channelmenu_diy/li.gif) no-repeat;"></div>	<a href="page/case/case.php" target="_self" class="channelmenu_main" id="channelmenu_main_5" onMouseOver="showSubMenu('channelmenu_main','channelmenu_sub',5)">成功案例</a><div id="menuright" style="float:left;height:27px;width:2px;margin-right:5px;background:url(menu/templates/images/channelmenu_diy/li.gif) no-repeat;"></div>	<a href="page/feedback/feedback.php" target="_self" class="channelmenu_main" id="channelmenu_main_6" onMouseOver="showSubMenu('channelmenu_main','channelmenu_sub',6)">需求反馈</a><div id="menuright" style="float:left;height:27px;width:2px;margin-right:5px;background:url(menu/templates/images/channelmenu_diy/li.gif) no-repeat;"></div>	<a href="page/contact/contact.php" target="_self" class="channelmenu_main" id="channelmenu_main_7" onMouseOver="showSubMenu('channelmenu_main','channelmenu_sub',7)">联系方式</a><div id="menuright" style="float:left;height:27px;width:2px;margin-right:5px;background:url(menu/templates/images/channelmenu_diy/li.gif) no-repeat;"></div>

The processing function showSubMenu() under onMouseOver
Why can’t I find the place where this function is defined in the javascript code of the page?
Or this function has been defined by the system of? Just call it directly? Asking for detailed advice from experts. Waiting online. Bonus points as appropriate

Reply to discussion (solution)

JavaScript generally has internal and external writing methods:
1. Internal
Written in the head: 93f0f5c25f18dab9d176bd4f6de5d30e3f1c4e4b6b16bbbd69b2ee476dc4f83a2cacc6d41bbb37262a98f745aa00fbf09c3bca370b5104690d9ef395f2c5f8d1
or written anywhere in the body;
2. External calls:
For example:
3f0591908f72fab90f2d27e61ae06b4f2cacc6d41bbb37262a98f745aa00fbf0

Is your showSubMenu() method written on the page or in external js If it is written in an external js file, it is best to put it in93f0f5c25f18dab9d176bd4f6de5d30e3f0591908f72fab90f2d27e61ae06b4f2cacc6d41bbb37262a98f745aa00fbf0

Thank you so much