JS detects if username and password are correct

This article is a simple JavaScript detection username and password is correct function Oh, if you are JS beginners can look at this code OH.

<script language= ' JavaScript ' >
function XGJC (YHM,MM,XMM,QM)
{
if (yhm== "")
{
Alert (' username cannot be empty! ');
Document.de.yhm.focus ();
return false;
}
if (MM!=XMM)
{
Alert (' Two input passwords inconsistent! ');
Document.de.mm.focus ();
return false;
}
if (qm.length>=49)
{
Alert (' Signed too long! ');
Document.de.qm.focus ();
return false;
}
}

function ZCJC (YHM,MM,XMM,QM)
{
if (yhm== "")
{
Alert (' username cannot be empty! ');
Document.zc.yhm.focus ();
return false;
}
if (Yhm.indexof ("") >=0 | | Yhm.indexof ("<") >=0 | | Yhm.indexof (">") >=0 | | Yhm.indexof (".") >=0)
{
Alert (' username cannot have garbled! ');
Document.zc.yhm.focus ();
return false;
}

if (mm== "")
{
Alert (' Password cannot be empty! ');
Document.zc.mm.focus ();
return false;
}
if (MM!=XMM)
{
Alert (' Two input passwords inconsistent! ');
Document.zc.mm.focus ();
return false;
}
if (Mm.indexof ("") >=0 | | Mm.indexof ("<") >=0 | | Mm.indexof (">") >=0 | | Mm.indexof (".") >=0)
{
Alert (' Can't have garbled! ');
Document.zc.mm.focus ();
return false;
}
if (qm.length>=49)
{
Alert (' Signed too long! ');
Document.zc.qm.focus ();
return false;
}
}
</script>

Here is the HTML code

&lt;form name= "Zc" action= "TB_ZC.ASP?CZ=ZCCG" method= "POST" &gt;


&lt;div align= "left" &gt;


&lt;p&gt; Username:


&lt;input name= "YHM" type= "text" size= "&gt;


*&lt;br&gt;


Password:


&lt;input name= "mm" type= "password" size= "&gt;
"

*&lt;br&gt;


Password:


&lt;input name= "qxmm" type= "password" size= "&gt;
"

*&lt;br&gt;


Personality Signature:


&lt;input type= "text" Name= "QM" size= "" maxlength= "&gt;
"

&lt;br&gt;


e-mail:


&lt;input name= "Lxfs" type= "text" size= "M" maxlength= "&gt;
"

&lt;/p&gt;


&lt;p align= "center" &gt;


&lt;input type= "Submit" Name= "ZC" value= "registered" onclick= "Return ZCJC (Yhm.value,mm.value,qxmm.value,qm.valu e); &gt;


&lt;/p&gt;


&lt;/div&gt;


&lt;/form&gt;