demo演示地址:http://www.xuanfengge.com/demo/201308/textarea/demo1.html
因为textarea不支持自适应高度,就是定好高度或者是行数之后,超出部分就会显示滚动条,看起来不美观。
而用DIV来模拟时,首先遇到的问题是:div怎么实现输入功能?
可能我们还是第一次见到这个属性contenteditable,如一个普通的block元素上加个contenteditable="true"
就实现编辑,出现光标了。如
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contenteditable属性虽是HTML5里面的内容,但是IE似乎老早就支持此标签属性了。所以,兼容性方面还是不用太担心的。
CSS代码
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.textarea{ width: 400px; min-height: 20px; max-height: 300px; _height: 120px; margin-left: auto; margin-right: auto; padding: 3px; outline: 0; border: 1px solid #a0b3d6; font-size: 12px; line-height: 24px; padding: 2px; 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); } |
HTML代码
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CSS代码中,因为IE6不支持min/max,所以做了hack,其他的也好理解。
demo演示地址:http://www.xuanfengge.com/demo/201308/textarea/demo2.html
这个写法是用原生JS写的,考虑了很多兼容性问题,完全和新浪微博的回复效果一样的功能。有兴趣的童鞋可以仔细分析下代码。
CSS代码
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#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); } |
JavaScript代码
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/** * 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(); }; |
HTML代码(写在body里面的)
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var text = document.getElementById("textarea"); autoTextarea(text);// 调用
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方法三:文本框textarea根据输入内容自适应高度,使用scrollHeight方法
HTML代码:
JavaScript代码:
//code from http://caibaojian.com/textarea-autoheight.html
function makeExpandingArea(el) {
var timer = null;
//由于ie8有溢出堆栈问题,故调整了这里
var setStyle = function(el, auto) {
if (auto) el.style.height = 'auto';
el.style.height = el.scrollHeight + 'px';
}
var delayedResize = function(el) {
if (timer) {
clearTimeout(timer);
timer = null;
}
timer = setTimeout(function() {
setStyle(el)
}, 200);
}
if (el.addEventListener) {
el.addEventListener('input', function() {
setStyle(el, 1);
}, false);
setStyle(el)
} else if (el.attachEvent) {
el.attachEvent('onpropertychange', function() {
setStyle(el)
})
setStyle(el)
}
if (window.VBArray && window.addEventListener) { //IE9
el.attachEvent("onkeydown", function() {
var key = window.event.keyCode;
if (key == 8 || key == 46) delayedResize(el);
});
el.attachEvent("oncut", function() {
delayedResize(el);
}); //处理粘贴
}
}
var textarea = document.getElementById('textarea');
makeExpandingArea(textarea);
如果展示无滚动条textarea添加css元素 textarea{ overflow:hidden; }