方法一:div模擬textarea文本域輕鬆實現高度自適應
demo演示地址:http://www.xuanfengge.com/demo/201308/textarea/demo1.html
因爲textarea不支持自適應高度,就是定好高度或者是行數之後,超出部分就會顯示滾動條,看起來不美觀。
而用DIV來模擬時,首先遇到的問題是:div怎麼實現輸入功能?
可能我們還是第一次見到這個屬性contenteditable,如一個普通的block元素上加個contenteditable="true"
就實現編輯,出現光標了。如
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<div contenteditable="true"></div> |
contenteditable屬性雖是HTML5裏面的內容,但是IE似乎老早就支持此標籤屬性了。所以,兼容性方面還是不用太擔心的。
CSS代碼
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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代碼
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<div class="textarea" contenteditable="true"><br /></div> |
CSS代碼中,因爲IE6不支持min/max,所以做了hack,其他的也好理解。
方法二:文本框textarea根據輸入內容自適應高度
demo演示地址:http://www.xuanfengge.com/demo/201308/textarea/demo2.html
這個寫法是用原生JS寫的,考慮了很多兼容性問題,完全和新浪微博的回覆效果一樣的功能。有興趣的童鞋可以仔細分析下代碼。
CSS代碼
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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); } |
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/** * 文本框根據輸入內容自適應高度 * @param {HTMLElement} 輸入框元素 * @param {Number} 設置光標與輸入框保持的距離(默認0) * @param {Number} 設置最大高度(可選) */ 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代碼(寫在body裏面的)
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<textarea id="textarea" placeholder="回覆內容"></textarea> <script> var text = document.getElementById("textarea"); autoTextarea(text);// 調用 </script> |
方法三:文本框textarea根據輸入內容自適應高度,使用scrollHeight方法
HTML代碼:
<textarea id="textarea"></textarea>
JavaScript代碼:
//code from http://caibaojian.com/textarea-autoheight.html
function makeExpandingArea(el) {
var timer = null;
//由於ie8有溢出堆棧問題,故調整了這裏
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);
}); //處理粘貼
}
}
var textarea = document.getElementById('textarea');
makeExpandingArea(textarea);
如果展示無滾動條textarea添加css元素 textarea{ overflow:hidden; }