<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>textarea高度自适应</title>
<script src="../jquery-1.11.3.js"></script>
</head>
<body>
<textarea name="text" style="width: 300px;"></textarea>
<textarea name="text" style="width: 300px;"></textarea>
<script>
$(function () {
// 为每一个textarea绑定事件使其高度自适应
$.each($("textarea"), function(i, n){
autoTextarea($(n)[0]);
});
})
/**
* 文本框根据输入内容自适应高度
* {HTMLElement} 输入框元素
* {Number} 设置光标与输入框保持的距离(默认0)
* {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 = 'both';//如果不希望使用者可以自由的伸展textarea的高宽可以设置其他值
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>
</body>
</html>
