js文本域设置字数，剩余字数

<tr>
<td class="right" style="width:100px">
<label for="remarks">备注:</label>
</td>
<td class="left">
<textarea type="text" id="remarks" name="remarks" style="width:500px;height:100px" onkeydown="checkMaxInput(this,100)"
onkeyup="checkMaxInput(this,100)" onfocus="checkMaxInput(this,100)" onblur="checkMaxInput(this,100);resetMaxmsg()" class="easyui-validatebox"
data-options="required:false" ></textarea>
</td>
</tr>

 

//多行文本输入框剩余字数计算
function checkMaxInput(obj, maxLen) {
if (obj == null || obj == undefined || obj == "") {
return;
}
if (maxLen == null || maxLen == undefined || maxLen == "") {
maxLen = 100;
}

var strResult;
var $obj = $(obj);
var newid = $obj.attr("id") + 'msg';

if (obj.value.length > maxLen) { //如果输入的字数超过了限制
obj.value = obj.value.substring(0, maxLen); //就去掉多余的字
strResult = '<span id="' + newid + '" class=\'Max_msg\' ><br/>剩(' + (maxLen - obj.value.length) + ')字</span>'; //计算并显示剩余字数
}
else {
strResult = '<span id="' + newid + '" class=\'Max_msg\' ><br/>剩(' + (maxLen - obj.value.length) + ')字</span>'; //计算并显示剩余字数
}

var $msg = $("#" + newid);
if ($msg.length == 0) {
$obj.after(strResult);
}
else {
$msg.html(strResult);
}
}

//清空剩除字数提醒信息
function resetMaxmsg() {
$("span.Max_msg").remove();
}