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Using JS to achieve: The dynamic display of page components, hiding

Source: Internet
Author: User
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<!--======= demo.html page: ==========-->
<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 transitional//en" >
<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<meta name= "generator" content= "EditPlus" >
<meta name= "Author" content= "Qiujy" >
<meta name= "Keywords" content= "" >
<meta name= "Description" content= "" >
</HEAD>

<BODY>
<TABLE>
&LT;TR id = "Toshowtextarea" style= "Display:block" >
<td><textarea name= "Area" rows= "3" cols= "maxlength=" "style=" Behavior:url (MAXLENGTH.HTC) "onKeyUp=" Javascript:countcharnum (); " ></TEXTAREA></TD>
<td><font color= "Red" > can still enter </font>
<input type= "text" name= "Limit" size= "3" id= "Limit" value= "maxlength=" 3 "readonly=" true "/><font color=" Red "> Chinese characters </font>
</TD>
</TR>
&LT;TR id = "Toshowseletlist" style= "Display:none" >
<td><select name= "Test" >
<option value= "a" >aaaaaaa</option>
<option value= "B" >bbbbbbb</option>
<option value= "C" >ccccccc</option>
<option value= "D" >ddddddd</option>
</SELECT></TD>
<TD> Please select </TD>
</TR>
<TR>
&LT;TD colspan= "2" ><input type= "button" Name= "BUT1" value= "Display text field" >
<input type= "button" Name= "But2" value= "Display drop-down list" ></TD>
</TR>
</TABLE>
</BODY>
</HTML>
<script language= "JavaScript" >
<!--
function Showtextarea () {
toshowtextarea.style.display= "Block";
Toshowseletlist.style.display= "None";
}
function Showselectlist () {
Toshowtextarea.style.display= "None";
toshowseletlist.style.display= "Block";
}

function Countcharnum () {
Limit.value = 50-area.value.length;
}
-->
</SCRIPT>

Maximum text limits for text fields I tried a lot of ways, but only the following is the most effective, (nothing else prevents the user from having to paste the shell)

<!--The following is the HTC used to verify the maximum length limit of the text field: named MAXLENGTH.HTC-->

<public:component id= "Bhvmaxlength" urn= "Maf:maxlength" >
<public:property name= "MaxLength"/>
<public:attach event= "onkeypress" handler= "dokeypress"/>
<public:attach event= "onkeydown" handler= "Dokeydown"/>
<public:attach event= "Onbeforepaste" handler= "Dobeforepaste"/>
<public:attach event= "Onpaste" handler= "Dopaste"/>
<public:attach event= "Oncontentready" handler= "Init"/>

<script language= "JScript" >
JS used to limit the maximum length of a text field
function dokeypress ()
{
if (!isnan (maxLength))
{
MaxLength = parseint (maxLength)
var OTR = Element.document.selection.createRange ()
if (oTR.text.length >= 1)
Event.returnvalue = True
else if (Value.length > MaxLength-1)
Event.returnvalue = False
}
}

function Dokeydown ()
{
settimeout (function ()
{
MaxLength = parseint (maxLength)
if (!isnan (maxLength))
{
if (Element.value.length > MaxLength-1)
{
var OTR = Window.document.selection.createRange ()
Otr.movestart ("character", -1* (Element.value.length-maxlength))
Otr.text = ""
}
}
},1)
}

function Dobeforepaste ()
{
if (!isnan (maxLength))
Event.returnvalue = False
}

function Dopaste ()
{
if (!isnan (maxLength))
{
Event.returnvalue = False
MaxLength = parseint (maxLength)
var OTR = Element.document.selection.createRange ()
var iinsertlength = maxlength-value.length + oTR.text.length
var sData = window.clipboardData.getData ("Text"). substr (0, Iinsertlength)
Otr.text = SData;
}
}

function init ()
{
MaxLength = parseint (maxLength)
if (!isnan (maxLength))
{
Element.value = element.value.substr (0, MaxLength)
}
}
</SCRIPT>

</PUBLIC:COMPONENT>


The following is an effect chart

The effect of clicking "Show drop down list"




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