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最近论坛里有人问，如何实现textarea文本编辑器的计数功能。我在这里特意的写一篇文章来实现textarea或input标签的计数功能。
实现原理如下：首先需要实现键盘事件的监听功能，在输入内容(插入、删除、修改)时进行长度统计，达到规定的长度后，在输入的内容将被受到限制。
先看下运行效果：
完整实现代码如下：
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk" />
<title>POPHint & statInput 整合效果</title>
<style type="text/css">
* {padding: 0; margin: 0}
body {margin: 30em; font: 12px Tahoma; background: #EAEAEA; color: #333333; line-height: 20px}
input, textarea {font: 12px Tahoma; color: #666666; padding: 2px; border: solid 1px #DBDBDB}
textarea {padding: 5px; line-height: 20px}
p {margin: 1em 0}
li {height: 1%; overflow: hidden; list-style-type: none}
a {color: #666666; text-decoration: none}
a:hover {color: #333333}
.r {float: right}
.l {float: left}
.b {font-weight: bold}
.gray {color: #666666; margin-top: 8px}
.light {color:#FF6600; margin: 0 5px}
.case {display: block; padding: 0 2em 2em 2em; border: solid 1px #EAEAEA; background: #FFFFFF; margin-bottom: 2em; height: 1%; overflow: hidden}
.title {display:block; padding: .5em 2em .5em 1em; margin: 0 -2em 2em -2em; font-weight: bold; color: #000000; background: #FAFAFA; border-bottom: solid 1px #EAEAEA}
.call {display:block;}
.key {display: block; width: 6em; float: left}
.type {display: block; width: 6em; float: left}
.info {padding-left: 2em}
.demo {margin-bottom: 2em}
/* popHint Style */
#popHint {position: absolute; line-height: normal}
#popHint .popLeft, #popHint .popRight, #popHint .popAngle span, #popHintText, #popHint .popIcon {}
#popHint .popHeader {height: 1%; overflow: hidden !important; overflow /**/: visible}
#popHint .popLeft {float: left; width: 5px; height: 24px; background-position: 0 0; background-repeat: no-repeat}
#popHint .popRight {float: left; width: 5px; height: 24px; background-position: -10px -25px; background-repeat: no-repeat}
#popHint .popAngle {clear: both; position: relative; height: 10px}
#popHint .popAngle span {position: absolute; top: -3px; left: 15px; width: 7px; height: 13px; background-position: 0 -75px; background-repeat: no-repeat}
#popHintText {float: left; color: #975400; height: 19px !important; height /**/: 24px; padding: 5px 0 0 0; white-space: nowrap; background-position: 0 -50px; background-repeat: repeat-x; overflow: hidden}
#popHintText .popIcon {float: left; width: 15px; height: 10px; margin: 1px 3px 0 0}
#popHint .wrong {background-position: 0 -90px; background-repeat: no-repeat}
#popHint .right {background-position: 0 -105px; background-repeat: no-repeat}
</style>
<script>
var $ = function(element) {// 获取元素
return (typeof(element) == 'object' ? element : document.getElementById(element));
},
brower = function() {// 判断浏览器
var ua = navigator.userAgent.toLowerCase();
var os = new Object();
os.isFirefox = ua.indexOf ('gecko') != -1;
os.isOpera = ua.indexOf ('opera') != -1;
os.isIE = !os.isOpera && ua.indexOf ('msie') != -1;
os.isIE7 = os.isIE && ua.indexOf ('7.0') != -1;
return os;
},
// 生成元素到refNode
appendElement = function(tagName, Attribute, strHtml, refNode) {
var cEle = document.createElement(tagName);
// 属性值
for (var i in Attribute){
cEle.setAttribute(i, Attribute[i]);
}
cEle.innerHTML = strHtml;
refNode.appendChild(cEle);
return cEle;
},
// 获取元素坐标
getCoords = function(node){
var x = node.offsetLeft;
var y = node.offsetTop;
var parent = node.offsetParent;
while (parent != null){
x += parent.offsetLeft;
y += parent.offsetTop;
parent = parent.offsetParent;
}
return {x: x, y: y};
},
// 事件操作(可保留原有事件)
eventListeners = [],
findEventListener = function(node, event, handler){
var i;
for (i in eventListeners){
if (eventListeners[i].node == node && eventListeners[i].event == event && eventListeners[i].handler == handler){
return i;
}
}
return null;
},
myAddEventListener = function(node, event, handler){
if (findEventListener(node, event, handler) != null){
return;
}
if (!node.addEventListener){
node.attachEvent('on' + event, handler);
}else{
node.addEventListener(event, handler, false);
}
eventListeners.push({node: node, event: event, handler: handler});
},
removeEventListenerIndex = function(index){
var eventListener = eventListeners[index];
delete eventListeners[index];
if (!eventListener.node.removeEventListener){
eventListener.node.detachEvent('on' + eventListener.event,
eventListener.handler);
}else{
eventListener.node.removeEventListener(eventListener.event,
eventListener.handler, false);
}
},
myRemoveEventListener = function(node, event, handler){
var index = findEventListener(node, event, handler);
if (index == null) return;
removeEventListenerIndex(index);
},
cleanupEventListeners = function(){
var i;
for (i = eventListeners.length; i > 0; i--){
if (eventListeners[i] != undefined){
removeEventListenerIndex(i);
}
}
};
function statInput(e, _max, _exp) {
e = $(e);
_max = parseInt(_max);
_max = isNaN(_max) ? 0 : _max;
_exp = _exp==undefined ? {} : _exp;
if(e==null || _max==0) {
alert('statInput初始化失败！');
return;
}
var _brower = brower();// 浏览器
// 输出对象
_objMax = _exp._max==undefined ? null : $(_exp._max),
_objTotal = _exp._total==undefined ? null : $(_exp._total),
_objLeft = _exp._left==undefined ? null : $(_exp._left),
// 弹出提示
_hint = _exp._hint==undefined ? null : _exp._hint;
// 初始统计
if(_objMax!=null) _objMax.innerHTML = _max;
if(_objTotal!=null) _objTotal.innerHTML = 0;
if(_objLeft!=null) _objLeft.innerHTML = 0;
// 设置监听事件
if(_brower.isIE) {
myAddEventListener(e, "propertychange", stat);
}else{
myAddEventListener(e, "input", stat);
}
// 统计函数
var _len, _olen, _lastRN, _sTop;
_olen = _len = 0;
function stat() {
_len = e.value.length;
if(_len==_olen) return; // 防止用计时器监听时做无谓的牺牲...
if(_len>_max) {
_sTop = e.scrollTop;
// 避免IE最后俩字符为'\r\n'.导致崩溃...
_lastRN = (e.value.substr(_max-1, 2) == "\r\n");
e.value = e.value.substr(0, (_lastRN ? _max-1 : _max));
if(_hint==true) popHint(e, "超过最大输入限制了~~.");
// 解决FF老是跑回顶部
if(_brower.isFirefox) e.scrollTop = e.scrollHeight;
}
_olen = _len = e.value.length;
// 显示已输入字数
if(_objTotal!=null) _objTotal.innerHTML = _len;
// 显示剩余可输入字数
if(_objLeft!=null) _objLeft.innerHTML = (_max-_len)<0 ? 0 : (_max-_len);
}
stat();
}
function popHint(obj, msg, initValues) {
var
_obj = $(obj),
_objHint = $("popHint"),
_msg = msg,
_init = initValues;
// 初始化失败...
if(_obj==undefined || _msg==undefined || _msg=="") return;
// 设置初始值
_init = _init==undefined ? {_type : "wrong", _event : "click"} : _init;
// obj如果不可见。设置弹出对象为obj父元素
if(_obj.style.display=='none' || _obj.style.visibility=='hidden' || _obj.getAttribute('type')=='hidden') _obj = _obj.parentNode;
var
_type = null,
_event = null,
_place = getCoords(_obj),
_marTop = null,
_objText = $("popHintText"),
// 初始化
init = function() {
var _hint = _obj.getAttribute("hint");
if(_hint=="false") return;
// 有的时候initValues不为空.但是只设置一个值...避免发生错误.再次设置初始值...
_type = _init._type==undefined ? "wrong" : _init._type;
_type = _type.toLowerCase();
_event = _init._event==undefined ? "click" : _init._event;
_event = _event.toLowerCase();
var _Html = "<div id=\"popHeader\">" +
" <div class=\"popLeft\"></div>" +
" <div id=\"popHintText\"></div>" +
" <div class=\"popRight\"></div>" +
"</div>"+
"<div class=\"popAngle\"><span></span></div>"
if(_objHint==null) {
_objHint = appendElement("div", {"id" : "popHint"}, _Html, document.body);
_objHint.style.display = "none";
_objText = $("popHintText");
}
show();
},
// 显示
show = function() {
_objHint.style.display = "";
_marTop = _objHint.offsetHeight;
_msg = "<span class=\"popIcon "+ _type +"\"></span>"+ _msg;
_objText.innerHTML = _msg;
_objHint.style.left = _place.x +"px";
_objHint.style.top = (_place.y-_marTop+8) +"px";
// 关闭触发事件
switch(_event) {
case "blur" :
myAddEventListener(_obj, 'blur', hide);
break;
//default :
case "click" :
myAddEventListener(document, 'mousedown', hide);
break;
}
},
// 关闭
hide = function() {
_objHint.style.display = "none";
_objText.innerHTML = "";
// 移除关闭触发事件
myRemoveEventListener(_obj, 'blur', hide);
myRemoveEventListener(document, 'mousedown', hide);
};
init();
}
myAddEventListener(window, "load", testStatInput);
function testStatInput(){
statInput('Test_1', 10, {_max : 'stat_max', _total : 'stat_total', _left : 'stat_left', _hint : true});
}
</script>
</head>
<body>
<div class="case">
<div class="title"><a href="#" class="r">Top</a>statInput?调用方法</div>
<div class="b">statInput(Element, MaxLen, {objMax, objTotal, objLeft, Hint});</div>
<ul class="info gray">
<li><span class="key">Element：</span><span class="type">Object</span>限制统计对象?(*必须)</li>
<li><span class="key">MaxLen：</span><span class="type">Number</span>最大可输入长度?(*必须)</li>
<li><span class="key">objMax：</span><span class="type">Object</span>显示最大输入长度对象?(*可选)</li>
<li><span class="key">objTotal：</span><span class="type">Object</span>显示输入统计对象?(*可选)</li>
<li><span class="key">objLeft：</span><span class="type">Object</span>显示可输入长度对象?(*可选)</li>
<li><span class="key">Hint：</span><span class="type">Boolean</span>当长度超出上限时，是否提示?(*可选)</li>
</ul>
</div>
<div class="case">
<div class="title"><a href="#" class="r">Top</a>statInput 演示</div>
<textarea name="Test_1" id="Test_1" rows="3" style="width: 99%" >业余草 http://www.xttblog.com</textarea>
<div class="gray">最多可输入<span id="stat_max" class="b light"></span>，当前共<span id="stat_total" class="b light"></span>，还可输入<span id="stat_left" class="b light"></span></div>
</div>
<div class="case">
<div class="title"><a href="#" class="r">Top</a>popHint?调用方法(目前只支持单行)</div>
<div class="b">popHint(Element, Hint, {Type, Event});</div>
<ul class="info gray">
<li><span class="key">Element：</span><span class="type">Object</span>弹出对象。根据它来定位的。??(*必须)</li>
<li><span class="key">Hint：</span><span class="type">String</span>弹出的信息，支持HTML可是不能换行。??(*必须)</li>
<li><span class="key">Type：</span><span class="type">String</span>弹出类型。其实说类型是不对的。只是定义个图标而已...(可自己在样式里加很多很多"类型")??(*可选)</li>
<li><span class="key">Event：</span><span class="type">String</span>关闭触发事件。目前只能绑定单个事件(默认click=document.onmousedown,blur=Element.onblur)??(*可选)</li>
</ul>
<br />
<span style="color: #333333" class="b">详见：<a href="http://www.xttblog.com/?p=461" target="_blank" >http://www.xttblog.com/?p=461</a></span>
</div>
</body>
</html>
版权声明：本文为博主原创文章，未经博主允许不得转载。原文地址：http://www.xttblog.com/?p=459
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本文原文出处：业余草： » 统计textarea输入个数并限制输入长度特效提示