 
/* 
*長(zhǎng)度跟蹤器 
*v2.1.0 
*bind2Id:用于顯示長(zhǎng)度變化的元素的id 
*max:最大長(zhǎng)度 
*msgWrap:提示信息(必須要有一個(gè)"-"占位符) 
*eg:$('#input').lenTracer({bind2Id:'myTracer',max:150,msgWrap:'您還可以輸入-個(gè)字符'}); 
*author:liujg1015@gmail.com 
*/ 
(function ($) { 
var zw_validate = function (el, option) { 
this.el = $(el); 
this.bindEl = false; 
this.setting = { 
bind2Id: false, 
max: 100, 
msgWrap: '您還可以輸入-個(gè)字符' 
}; 
if (option) { 
$.extend(this.setting, option); 
this.init(); 
} 
}; 
zw_validate.prototype = { 
init: function () { 
var _this = this; 
this.bindEl = $('#' + this.setting.bind2Id); 
this.el.focus(function () { _this.start(); }).blur(function () { _this.dispose(); }); 
this.el.css({ paddingBottom: 20 }); 
this.initMsg(); 
}, 
initMsg: function () { 
var wrap = this.setting.msgWrap.split('-'); 
this.bindEl.text(this.setting.max - this.count().total).before(wrap[0]).after(wrap[1]); 
}, 
count: function () { 
var _val = this.el.val(); 
var _len = _val.length; 
var _rowCount = 0; 
var _enterLen = 0; 
var _partten = /\n+/g; 
if (_len > 0 && _partten.test(_val)) { 
_enterLen += 3; 
while ((result = _partten.exec(_val)) != null) { 
if ((result.index + 1 + _enterLen) > this.setting.max) { 
break; 
} 
_enterLen += 3; 
} 
_rowCount = _val.match(_partten).length; 
} 
return { total: (_len + _rowCount * 3), enterLen: _enterLen }; 
}, 
start: function () { 
var _this = this; 
_this.timer = setInterval(function () { 
var _val = _this.el.val(); 
var _rlt = _this.count(); 
if (_rlt.total > _this.setting.max) { 
if (_rlt.enterLen > 0) { 
_this.el.val(_val.substr(0, _this.setting.max - _rlt.enterLen)); 
} 
else { 
_this.el.val(_val.substr(0, _this.setting.max)); 
} 
_this.bindEl.text(_this.setting.max - _this.count().total); 
return; 
} 
_this.bindEl.text(_this.setting.max - _rlt.total); 
}, 300); 
}, 
dispose: function () { 
clearInterval(this.timer); 
}, 
restore: function () { 
this.bindEl.text(this.setting.max - this.el.val().length); 
} 
}; 
$.fn.extend({ 
lenTracer: function (option) { 
return new zw_validate(this, option); 
} 
}); 
})(jQuery); 

一、上面是計(jì)數(shù)器的腳本，可將腳本貼到j(luò)s文件中，然后在html里面添加引用。

復(fù)制代碼代碼如下:

 
<html> 
<head> 
<title>demo</title> 
</head> 
<body> 
<table> 
<tr> 
<td> 
標(biāo)題 
</td> 
<td> 
<input type="text" id="title" /> 
<span id="titlelen"></span> 
</td> 
</tr> 
<tr> 
<td> 
評(píng)論 
</td> 
<td> 
<textarea cols="5" rows="5" id="comment"></textarea> 
<span id="commentlen"></span> 
</td> 
</tr> 
</table> 
<script src="../scripts/jquery.js" type="text/javascript"></script> 
<script src="../scripts/lentracer.js" type="text/javascript"></script> 
<script type="text/javascript"> 
$(document).ready(function(){ 
$('#title).lenTracer({ bind2Id: titlelen, max: 50}); 
$('#comment).lenTracer({ bind2Id: commentlen, max: 200, msgWrap: '剩余-字' }); 
}); 
</script> 
</body> 
</html> 

二、上面的代碼是展示如何使用。
這個(gè)計(jì)數(shù)器是自己用jQuery寫(xiě)的，因此要依賴(lài)于jQuery庫(kù)函數(shù)。能計(jì)算回車(chē)符，因?yàn)樵趖extarea里面的回車(chē)符提交到后臺(tái)后是'\r\n'。歡迎批評(píng)、指正。

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