这 可能会 有所帮助（可能最好使用jQuery，onDomReady并毫不干扰地将keydown事件添加到textarea），但已在IE7和FF3中进行了测试：
<html>
<head><title>Test</title></head>
<body>
<script type="text/javascript">
var keynum, lines = 1;
function limitLines(obj, e) {
// IE
if(window.event) {
keynum = e.keyCode;
// netscape/Firefox/Opera
} else if(e.which) {
keynum = e.which;
}
if(keynum == 13) {
if(lines == obj.rows) {
return false;
}else{
lines++;
}
}
}
</script>
<textarea rows="4" onkeydown="return limitLines(this, event)"></textarea>
</body>
</html>
*编辑-说明：如果按下ENTER键，它将捕获按键，并且如果textarea中的行与textarea的行数相同，则不添加新行。否则，它将增加行数。
考虑到人们仍然在回答这个问题，我想我会尽可能地对其进行更新以处理粘贴，删除和剪切。
<html>
<head>
<title>Test</title>
<style>
.limit-me {
height: 500px;
width: 500px;
}
</style>
</head>
<body>
<textarea rows="4" class="limit-me"></textarea>
<script>
var lines = 1;
function getKeyNum(e) {
var keynum;
// IE
if (window.event) {
keynum = e.keyCode;
// netscape/Firefox/Opera
} else if (e.which) {
keynum = e.which;
}
return keynum;
}
var limitLines = function (e) {
var keynum = getKeyNum(e);
if (keynum === 13) {
if (lines >= this.rows) {
e.stopPropagation();
e.preventDefault();
} else {
lines++;
}
}
};
var setNumberOfLines = function (e) {
lines = getNumberOfLines(this.value);
};
var limitPaste = function (e) {
var clipboardData, pastedData;
// Stop data actually being pasted into div
e.stopPropagation();
e.preventDefault();
// Get pasted data via clipboard API
clipboardData = e.clipboardData || window.clipboardData;
pastedData = clipboardData.getData('Text');
var pastedLines = getNumberOfLines(pastedData);
// Do whatever with pasteddata
if (pastedLines <= this.rows) {
lines = pastedLines;
this.value = pastedData;
}
else if (pastedLines > this.rows) {
// alert("Too many lines pasted ");
this.value = pastedData
.split(/\r\n|\r|\n/)
.slice(0, this.rows)
.join("\n ");
}
};
function getNumberOfLines(str) {
if (str) {
return str.split(/\r\n|\r|\n/).length;
}
return 1;
}
var limitedElements = document.getElementsByClassName('limit-me');
Array.from(limitedElements).forEach(function (element) {
element.addEventListener('keydown', limitLines);
element.addEventListener('keyup', setNumberOfLines);
element.addEventListener('cut', setNumberOfLines);
element.addEventListener('paste', limitPaste);
});
</script>
</body>
</html>
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