teatarea 高度自适应方法总结

方法一：div模拟textarea文本域轻松实现高度自适应

<div class="textarea" contenteditable="true"> </div>

说明：

1、 react中可以使用 onFocus 等函数 实现交互

2、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。

方法二：文本框textarea根据输入内容自适应高度

说明：这个写法是用原生JS写的，兼容性问题良好； 核心代码：

css代码

#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: inset0 1px 3px rgba(0, 0, 0, 0.1), 0 0 8px rgba(82, 168, 236, 0.6);
}

JavaScript代码

/**

* 文本框根据输入内容自适应高度

* @param {elem} 输入框元素

* @param {extra} 设置光标与输入框保持的距离(默认0)

* @param {maxHeight} 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

<textarea id="textarea" placeholder="回复内容"></textarea>

    <script>
        var text = document.getElementById("textarea");
        autoTextarea(text);// 调用
    </script

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

<textarea id="textarea"></textarea>

css代码

#stextarea{
  overflow:hidden;
}

JavaScript代码

function autoTextAreaHeight(el) {
    var timer = null;
    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');
autoTextAreaHeight(textarea);