<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>textarea限制输入字符</title> </head> <body> <textarea name='test' onkeyup='textAreaChange(this)' onkeydown='textAreaChange(this)' rows='5'></textarea> <div class='text-right'> <em style='color:red'>200</em>/<span>200</span> </div> </body> <script src="http://libs.baidu.com/jquery/1.11.3/jquery.min.js"></script> <script type="text/javascript"> //显示限制输入字符method function textAreaChange(obj){ var $this = $(obj); var count_total = $this.next().children('span').text(); var count_input = $this.next().children('em'); var area_val = $this.val(); if(area_val.len()>count_total){ area_val = autoAddEllipsis(area_val,count_total);//根据字节截图内容 $this.val(area_val); count_input.text(0);//显示可输入数 }else{ count_input.text(count_total - area_val.len());//显示可输入数 } } //得到字符串的字节长度 String.prototype.len = function(){ return this.replace(/[^\x00-\xff]/g, "xx").length; }; /* * 处理过长的字符串，截取并添加省略号 * 注：半角长度为1，全角长度为2 * pStr:字符串 * pLen:截取长度 * return: 截取后的字符串 */ function autoAddEllipsis(pStr, pLen) { var _ret = cutString(pStr, pLen); var _cutFlag = _ret.cutflag; var _cutStringn = _ret.cutstring; return _cutStringn; } /* * 取得指定长度的字符串 * 注：半角长度为1，全角长度为2 * pStr:字符串 * pLen:截取长度 * return: 截取后的字符串 */ function cutString(pStr, pLen) { // 原字符串长度 var _strLen = pStr.length; var _tmpCode; var _cutString; // 默认情况下，返回的字符串是原字符串的一部分 var _cutFlag = "1"; var _lenCount = 0; var _ret = false; if (_strLen <= pLen/2){_cutString = pStr;_ret = true;} if (!_ret){ for (var i = 0; i < _strLen ; i++ ){ if (isFull(pStr.charAt(i))){_lenCount += 2;} else {_lenCount += 1;} if (_lenCount > pLen){_cutString = pStr.substring(0, i);_ret = true;break;} else if(_lenCount == pLen){_cutString = pStr.substring(0, i + 1);_ret = true;break;} } } if (!_ret){_cutString = pStr;_ret = true;} if (_cutString.length == _strLen){_cutFlag = "0";} return {"cutstring":_cutString, "cutflag":_cutFlag}; } /* * 判断是否为全角 * * pChar:长度为1的字符串 * return: true:全角 * false:半角 */ function isFull (pChar){ if((pChar.charCodeAt(0) > 128)){return true;} else{return false;} } </script> </html>
