textarea如何实现高度自适应（不出现滚动条）
1.js实现
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>文本框根据输入内容自适应高度</title>
<style type="text/css">
h2 {
text-align: center;
margin: 50px auto;
}
#textarea {
display: block;
margin: 0 auto;
overflow: hidden;
width: 550px;
font-size: 14px;
height: 18px;
line-height: 24px;
padding: 2px;
}
textarea {
outline: 0 none;
border-color: rgba(82, 168, 236, 0.8);
box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.1), 0 0 8px rgba(82, 168, 236, 0.6);
}
</style>
<script>
/**
* 文本框根据输入内容自适应高度
* @param {HTMLElement} 输入框元素
* @param {Number} 设置光标与输入框保持的距离(默认0)
* @param {Number} 设置最大高度(可选)
*/
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();
};
</script>
<script async src="http://c.cnzz.com/core.php"></script>
</head>
<body>
<h2>文本框根据输入内容自适应高度</h2>
<textarea id="textarea" placeholder="回复内容"></textarea>
<script>
var text = document.getElementById("textarea");
autoTextarea(text); // 调用
</script>
</body>
</html>
2.div模拟textarea文本域轻松实现高度自适应
方法一：div模拟textarea文本域轻松实现高度自适应
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>div模拟textarea文本域轻松实现高度自适应</title>
<style>
h2 {
text-align: center;
margin: 50px auto;
}
.test_box {
width: 400px;
min-height: 20px;
/*设置最小高度*/
max-height: 1000px;
/*设置最大高度超过300px时出现滚动条*/
_height: 120px;
margin-left: auto;
margin-right: auto;
padding: 13px;
outline: 0;
border: 1px solid #a0b3d6;
font-size: 16px;
line-height: 24px;
word-wrap: break-word;
overflow-x: hidden;
overflow-y: auto;
border-color: rgba(82, 168, 236, 0.8);
box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.1), 0 0 8px rgba(82, 168, 236, 0.6);
}
</style>
</head>
<body>
<h2>div模拟textarea文本域轻松实现高度自适应</h2>
<div class="test_box" contenteditable="true">
<br />
</div>
</body>
</html>