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  • textarea高度自适应

    <!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=" 300px;"></textarea>
    <textarea name="text" style=" 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>
    
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  • 原文地址:https://www.cnblogs.com/gkgkgk/p/15668604.html
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