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Commonly used JavaScript limit input character number code

Source: Internet
Author: User
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<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "http://www.jzread.com/TR/xhtml1/DTD/ Xhtml1-transitional.dtd ""
<html xmlns= "http://www.jzread.com/1999/xhtml"
<head>
< Meta http-equiv= "Content-type" content= "HTML; Charset=utf-8 "/>
<style type= text/css Tutorial" media= "screen"
body{margin:0px;
div{width:400px; margin:0px Auto;
Div h3{background: #CCCCCC; font-size:14px; font-weight:bold; text-align:center; line-height:22px; margin:6px 0px; padding:0px;
Div textarea{width:388px height:120px border: #999999 1px solid; margin:0px; padding:0px; font-size:12px; padding : 5px; line-height:16px;
Div p{font-size:12px; margin:0px; line-height:22px;}
Div p span{color: #FF6600; font-weight:bold;}
</style>
<title>javascript Limit the maximum number of characters entered in the text box </title>
</head>

<body>
<div>
<h3> character number Test </h3>
<textarea rows= "cols=" onkeypress= "return Checkmaxlength (this,20)" ></textarea>
<p> Max <span>20</span> characters. </p>
</div>

<script type= "Text/javascript Tutorial" >
function Checkmaxlength (otextarea,maxlength) {
return otextarea.value.length!=maxlength;
}
</script>
</body>
</html>

Programme II

<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "http://www.jzread.com/TR/xhtml1/DTD/ Xhtml1-transitional.dtd ""
<html xmlns= "http://www.jzread.com/1999/xhtml"
<head>
< Meta http-equiv= "Content-type" content= "HTML; Charset=utf-8 "/>
<style type=" text/css "media=" screen "
body{margin:0px;
div{width:400px; margin:0px Auto;
Div h3{background: #CCCCCC; font-size:14px; font-weight:bold; text-align:center; line-height:22px; margin:6px 0px; padding:0px;
Div textarea{width:388px height:120px border: #999999 1px solid; margin:0px; padding:0px; font-size:12px; padding : 5px; line-height:16px;
Div p{font-size:12px; margin:0px; line-height:22px;}
Div p span{color: #FF6600; font-weight:bold;}
</style>
<title>javascript Limit the maximum number of characters entered in the text box </title>
</head>

<body>
<div>
<h3> character number Test </h3>
<textarea rows= "cols=" onkeyup= "Checkmaxlength (this,20)" onpaste= "Checkmaxlength (this,20)" ></ Textarea>
<p> Max <span>20</span> characters. </p>
</div>

<script type= "Text/javascript" >
function Checkmaxlength (area, maxLength) {
if (Area.value.length >maxlength) {
Area.value = area.value.substr (0, maxLength);
}
}
</script>
</body>
</html>

Programme III

<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "http://www.jzread.com/TR/xhtml1/DTD/ Xhtml1-transitional.dtd ""
<html xmlns= "http://www.jzread.com/1999/xhtml"
<head>
< Meta http-equiv= "Content-type" content= "HTML; Charset=utf-8 "/>
<style type=" text/css "media=" screen "
body{margin:0px;
div{width:400px; margin:0px Auto;
Div h3{background: #CCCCCC; font-size:14px; font-weight:bold; text-align:center; line-height:22px; margin:6px 0px; padding:0px;
Div textarea{width:388px height:120px border: #999999 1px solid; margin:0px; padding:0px; font-size:12px; padding : 5px; line-height:16px;
Div p{font-size:12px; margin:0px; line-height:22px;}
Div p span{color: #FF6600; font-weight:bold;}
</style>
<title>javascript Limit the maximum number of characters entered in the text box </title>
</head>

<body>
<div>
<h3> character test </h3>
<textarea rows= "cols=" Checkmaxlength (this,20) "onpaste=" Checkmaxlength (this,20) ></textarea>
<p> Max <span>20 </span> characters, one character 2 characters. </p>
</div>

<script type= "Text/javascript"
function checkmaxlength (area, maxLength) {
       var currentstr= "";
      for (var i=0,len=area.value.length;i<len;i++) {
            Currentstr+=area.value.charat (i);
           if (getcharlength (CURRENTSTR) >maxlength) {
                  Area.value=area.value.substr (0,i);
                    return;
          }
    }
}

function Getcharlength (str) {
var charlen=0;
for (Var i=0,len=str.length;i<len;i++) {
if (Str.charcodeat (i) >255) {
charlen+=2;
}else{
Charlen+=1;
}
}
return Charlen;
}
</script>
</body>
</html>

Programme III

<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "http://www.jzread.com/TR/xhtml1/DTD/ Xhtml1-transitional.dtd ""
<html xmlns= "http://www.jzread.com/1999/xhtml"
<head>
< Meta http-equiv= "Content-type" content= "HTML; Charset=utf-8 "/>
<style type=" text/css "media=" screen "
body{margin:0px;
div{width:400px; margin:0px Auto;
Div h3{background: #CCCCCC; font-size:14px; font-weight:bold; text-align:center; line-height:22px; margin:6px 0px; padding:0px;
Div textarea{width:388px height:120px border: #999999 1px solid; margin:0px; padding:0px; font-size:12px; padding : 5px; line-height:16px;
Div p{font-size:12px; margin:0px; line-height:22px;}
Div p span{color: #FF6600; font-weight:bold;}
</style>
<title>javascript Limit the maximum number of characters entered in the text box </title>
</head>

<body>
<div>
<h3> character test </h3>
<textarea rows= "cols=" Checkmaxlength (this,20) "onpaste=" return false; ></textarea>
<p> Max <span>20</span> characters, one kanji 2 characters, you can also enter <span>20</span> Character </p>
</div>

<script type= "Text/javascript"
var s=document.getelementsbytagname ("span") [1];
function Checkmaxlength (area, maxLength) {
      var currentstr= "";
   if (area.value.length==0) {s.innerhtml=maxlength}
      for (var i=0,len=area.value.length;i<len;i++) {
            Currentstr+=area.value.charat (i);
           if (getcharlength (CURRENTSTR) >maxlength) {
                  Area.value=area.value.substr (0,i);
                    return;
          }else{
              S.innerhtml=maxlength-getcharlengtH (CURRENTSTR);
    }
    }
}

Function Getcharlength (str) {
     var charlen=0
  for (Var i=0,len=str.length;i <len;i++) {
       if (str.charcodeat (i) >255) {
         charlen+=2;
   }else{
        charlen+=1
   }  
 }
  return Charlen
}
</script>
</body>
</html>
 

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