js控制文本域输入字数
<p><label>审核意见:</label> <textarea data-x="" data-y="" title="请填写（字数不多于100个）" name="auOpinion" id="auOpinion" onkeydown="changebyte1(this.value,100,'auOpinion');" onkeyup="changebyte1(this.value,100,'auOpinion');"></textarea> <font style="color: #ff0000">*</font> </p> <SPAN id="byte1_auOpinion" style="font-size: 12px;">(您还可输入</span><span id="byte2_auOpinion" style="color: #ff0000" style="font-size: 12px;">100</span><span id="byte3_auOpinion" style="font-size: 12px;">/100个字)</SPAN>
function changebyte1(value, length,textareaId) { var l = strlengthComm(value); if (l <= length) { document.getElementById("byte2_"+textareaId).innerText = (length - l); document.getElementById("byte1_"+textareaId).innerText = "(您还可输入"; document.getElementById("byte3_"+textareaId).innerText = "/"+length+"字)"; return true; } else { document.getElementById("byte2_"+textareaId).innerText = "(输入字数超出范围)"; document.getElementById("byte1_"+textareaId).innerText = ""; document.getElementById("byte3_"+textareaId).innerText = ""; document.getElementById(textareaId).value = substrComm(value, length); }}function substrComm(str, len) { if (!str || !len) { return ""; } //预期计数：中文2字节，英文1字节 var a = 0; //循环计数 var i = 0; //临时字串 var temp = ""; for (i = 0; i < str.length; i++) { //if (str.charCodeAt(i) > 255) { //按照预期计数增加2 //a += 2; //} else { a++; //} //如果增加计数后长度大于限定长度，就直接返回临时字符串 if (a > len) { return temp; } //将当前内容加到临时字符串 temp += str.charAt(i); }}function strlengthComm(str) { var l = str.length; var n = l; //for (var i = 0; i < l; i++) { //if (str.charCodeAt(i) < 0 || str.charCodeAt(i) > 255) { //n++; //} //} return n;}