js 截取字条串 文件框限制输入字符个数
//--以下方法为截取空字符串
function ltrim(str) { //截取左侧字符..
var pattern = new RegExp("^[\\s]+","gi");
return str.replace(pattern,"");
}
function rtrim(str) { //截取右侧字符....
var pattern = new RegExp("[\\s]+$","gi");
return str.replace(pattern,"");
}
function trim(str) { //截取左右字符...
return rtrim(ltrim(str));

}

使用：

var newRemark = trim(remark); //--截取字符串左右空格

//--文本框中限制输入字符为200
function chkTextareaLen(textareaId,counterId,maxLen) {
try{
var textareaValue = document.getElementById(textareaId).value;
var curLen = 0,substrLen = 0;

for (var i=0; i<textareaValue.length; i++) {
if (textareaValue.charCodeAt(i)>127 || textareaValue.charCodeAt(i)==94) {
curLen += 2;
} else {
curLen ++;
}

if(curLen > maxLen){
substrLen = i;
break;
}
}

if(curLen > maxLen) {
if(substrLen == 0) substrLen = maxLen;
document.getElementById(textareaId).value = textareaValue.substring(0,substrLen);
// alert("文本长度不能大于"+maxLen+"个字节(中文占2个字节)");
}else{
document.getElementById(counterId).innerHTML = maxLen - curLen;
}
}catch(e){}
}

定义一个多行文件框

<h:inputTextarea cols="82" rows="3" id="showRemark" value="" onkeydown="chkTextareaLen(this.id,'counterDeviceDesc',400)" onkeyup="chkTextareaLen(this.id,'counterDeviceDesc',400);"></h:inputTextarea>