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解决IE下textarea不识别maxlength属性的问题
首先先看一个比较简单的处理办法，代码如下：
$("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maxlength area.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maxlength area.val(area.val().substr(0, max)); //截断textarea的文本重新赋值 } } });代码很简单，但是体验不太好，就是你会看到textarea里面字符已经输进去了，然后进行的字符截断，这种体验明显和input中设置maxlength属性的效果(体验)不一样，但也能凑合着用了。下面我们看较复杂的实现，下面这种实现所得到的体验效果就和input设置maxlength的一样了
function onmyinput(o, maxLength) { if (o.value.length >= maxLength) { if (o.value.length > maxLength) o.value = http://www.mamicode.com/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 = http://www.mamicode.com/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 = http://www.mamicode.com/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 = http://www.mamicode.com/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 = http://www.mamicode.com/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 = http://www.mamicode.com/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 + ")"); } }}
解决IE下textarea不识别maxlength属性的问题
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