textarea内容可从后台读取或手动输入，常规输入后中文和数字会出现换行问题
<style>
#textarea {
display: block;
margin: 0 auto;
overflow: hidden;
250px;
font-size: 14px;
height: 100px;
line-height: 24px;
padding: 2px;
word-break: break-all;
word-wrap: break-word;
}
</style>
<body>
<textarea id="textarea" placeholder="回复内容">参加杨浦区党校的党员培训学习</textarea>
</body>
<script>
var autoTextarea = function(elem, extra, maxHeight) {
extra = extra || 0;
var isFirefox = !!document.getBoxObjectFor || 'mozInnerScreenX' in window,
isOpera = !!window.opera && !!window.opera.toString().indexOf('Opera'),
addEvent = function(type, callback) {
elem.addEventListener ?
elem.addEventListener(type, callback, false) :
elem.attachEvent('on' + type, callback);
},
getStyle = elem.currentStyle ? function(name) {
var val = elem.currentStyle[name];
if (name === 'height' && val.search(/px/i) !== 1) {
var rect = elem.getBoundingClientRect();
return rect.bottom - rect.top -
parseFloat(getStyle('paddingTop')) -
parseFloat(getStyle('paddingBottom')) + 'px';
};
return val;
} : function(name) {
return getComputedStyle(elem, null)[name];
},
minHeight = parseFloat(getStyle('height'));
elem.style.resize = 'none';
var change = function() {
var scrollTop, height,
padding = 0,
style = elem.style;
if (elem._length === elem.value.length) return;
elem._length = elem.value.length;
if (!isFirefox && !isOpera) {
padding = parseInt(getStyle('paddingTop')) + parseInt(getStyle('paddingBottom'));
};
scrollTop = document.body.scrollTop || document.documentElement.scrollTop;
elem.style.height = minHeight + 'px';
if (elem.scrollHeight > minHeight) {
if (maxHeight && elem.scrollHeight > maxHeight) {
height = maxHeight - padding;
style.overflowY = 'auto';
} else {
height = elem.scrollHeight - padding;
style.overflowY = 'hidden';
};
style.height = height + extra + 'px';
scrollTop += parseInt(style.height) - elem.currHeight;
document.body.scrollTop = scrollTop;
document.documentElement.scrollTop = scrollTop;
elem.currHeight = parseInt(style.height);
};
};
addEvent('propertychange', change);
addEvent('input', change);
addEvent('focus', change);
change();
};
var text = document.getElementById("textarea");
autoTextarea(text); // 调用
</script>
内容部分转载于 心郎 CSDN