$("textarea[maxlength]").keyup(function () {var area = $(this);var max = parseInt(area.attr("maxlength"), 10); //获取maxlength的值if (max > 0) {if (area.val().length > max) { //textarea的文本长度大于maxlengtharea.val(area.val().substr(0, max)); //截断textarea的文本重新赋值
                }}});//复制的字符处理问题$("textarea[maxlength]").blur(function () {var area = $(this);var max = parseInt(area.attr("maxlength"), 10); //获取maxlength的值if (max > 0) {if (area.val().length > max) { //textarea的文本长度大于maxlengtharea.val(area.val().substr(0, max)); //截断textarea的文本重新赋值
                }}});

function onmyinput(o, maxLength) {if (o.value.length >= maxLength) {if (o.value.length > maxLength) o.value = o.value.substring(0, maxLength);return false;}return true;
}
function mygetclipdata() {if (!document.all) {netscape.security.PrivilegeManager.enablePrivilege('UniversalXPConnect');var clip = Components.classes['@mozilla.org/widget/clipboard;1'].createInstance(Components.interfaces.nsIClipboard);var trans = Components.classes['@mozilla.org/widget/transferable;1'].createInstance(Components.interfaces.nsITransferable);trans.addDataFlavor('text/unicode');var str = Components.classes["@mozilla.org/supports-string;1"].createInstance(Components.interfaces.nsISupportsString);clip.getData(trans, clip.kGlobalClipboard);var str = new Object();var strLength = new Object();trans.getTransferData("text/unicode", str, strLength);if (str) str = str.value.QueryInterface(Components.interfaces.nsISupportsString);var pastetext;if (str) pastetext = str.data.substring(0, strLength.value / 2);return pastetext;} else {return window.clipboardData.getData("Text");}
}
function mysetclipdata(o) {if (!document.all) {netscape.security.PrivilegeManager.enablePrivilege('UniversalXPConnect');var clip = Components.classes['@mozilla.org/widget/clipboard;1'].createInstance(Components.interfaces.nsIClipboard);var trans = Components.classes['@mozilla.org/widget/transferable;1'].createInstance(Components.interfaces.nsITransferable);trans.addDataFlavor("text/unicode");var str = Components.classes["@mozilla.org/supports-string;1"].createInstance(Components.interfaces.nsISupportsString);str.data = o;trans.setTransferData("text/unicode", str, o.length * 2);var clipid = Components.interfaces.nsIClipboard;clip.setData(trans, null, clipid.kGlobalClipboard);} else {window.clipboardData.setData("Text", o);}
}
function onmypaste(o, maxLength) {var nMaxLen = o.getAttribute ? parseInt(maxLength) : "";if (!document.all) {//alert("不可能执行的代码");} else {if (document.selection.createRange().text.length > 0) {var ovalueandclipboarddata = o.value + window.clipboardData.getData("Text");if (o.getAttribute && ovalueandclipboarddata.length - document.selection.createRange().text.length > nMaxLen) {if (window.clipboardData.getData("Text").substring(0, document.selection.createRange().text.length + nMaxLen - o.value.length) != "") window.clipboardData.setData("Text", window.clipboardData.getData("Text").substring(0, document.selection.createRange().text.length + nMaxLen - o.value.length));else return false;}} else {var ovalueandclipboarddata = o.value + window.clipboardData.getData("Text");if (o.getAttribute && ovalueandclipboarddata.length > nMaxLen) {if (ovalueandclipboarddata.substring(0, nMaxLen - o.value.length) != "") window.clipboardData.setData("Text", ovalueandclipboarddata.substring(0, nMaxLen - o.value.length));else return false;}}return true;}
}
function onmykeypress(o, maxLength) {if (!document.all) {var nMaxLen = o.getAttribute ? parseInt(maxLength) : "";if (onmykeypress.caller.arguments[0].ctrlKey == true) {if (onmykeypress.caller.arguments[0].which == 118) {if (o.selectionStart < o.selectionEnd) {var ovalueandclipboarddata = o.value + mygetclipdata();if (o.getAttribute && (ovalueandclipboarddata.length - o.selectionEnd + o.selectionStart > nMaxLen)) {if (mygetclipdata().substring(0, o.selectionEnd - o.selectionStart + nMaxLen - o.value.length) != "") mysetclipdata(mygetclipdata().substring(0, o.selectionEnd - o.selectionStart + nMaxLen - o.value.length));else return false;}} else {var ovalueandclipboarddata = o.value + mygetclipdata();if (o.getAttribute && ovalueandclipboarddata.length > nMaxLen) {if (ovalueandclipboarddata.substring(0, nMaxLen - o.value.length) != "") mysetclipdata(ovalueandclipboarddata.substring(0, nMaxLen - o.value.length));else return false;}}return true;}}if (onmykeypress.caller.arguments[0].which == 0 || onmykeypress.caller.arguments[0].which == 8) return true;if (o.value.length >= maxLength) {if (o.selectionStart < o.selectionEnd) return true;if (o.value.length > maxLength) o.value = o.value.substring(0, maxLength);return false;} else return true;} else {if (document.selection.createRange().text.length > 0) return true;if (o.value.length >= maxLength) return false;else return true;}
}
window.onload = init_MaxLength;
function init_MaxLength() {var textAreaObj = document.getElementsByTagName("textarea");var maxLength;for (var i = 0; i < textAreaObj.length; i++) {maxLength = textAreaObj[i].getAttribute("maxLength") == null ? 0 : textAreaObj[i].getAttribute("maxLength");if (maxLength == 0) continue;textAreaObj[i].onpaste = function () {return onmypaste(this, maxLength)};textAreaObj[i].onkeypress = function () {return onmykeypress(this, maxLength)};textAreaObj[i].onpropertychange = function () {onmyinput(this, maxLength)};if (!document.all) {textAreaObj[i].setAttribute("oninput", "return onmyinput(this," + maxLength + ")");}}
}