JS textarea自动增高并隐藏滚动条

1:有个小bug,当按删除键时,高度不会自适应缩减

onpropertychange兼容IE


JQ写oninput的写法

$(selector).on("input oninput",function(){
    this.style.height=this.scrollHeight + 'px';
})

2:完美自适应

/**
* 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();
};
//调用
$(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]);
    });
})

3

$(function(){
    $.fn.autoHeight = function(){    
        function autoHeight(elem){
            elem.style.height = 'auto';
            elem.scrollTop = 0; //防抖动
            console.log(elem)
            elem.style.height = elem.scrollHeight + 'px';
        }
        this.each(function(){
            autoHeight(this);
            $(this).on('keyup', function(){
                autoHeight(this);
            });
        });     
    }                
    $('textarea').autoHeight();    
})

4

// html

// style .expandingArea { position:relative;} textarea{position:aboslate;top:0;left:0;} // js function makeExpandingArea(container) { var area = container.getElementsByTagName('textarea')[0]; var span = container.getElementsByTagName('span')[0]; if (area.addEventListener) { area.addEventListener('input', function() { span.textContent = area.value; }, false); span.textContent = area.value; } else if (area.attachEvent) { area.attachEvent('onpropertychange', function() { var html = area.value.replace(/\n/g, '
'); span.innerText = html; }); var html = area.value.replace(/\n/g, '
'); span.innerText = html; } if (window.VBArray && window.addEventListener) { //IE9 area.attachEvent("onkeydown", function() { var key = window.event.keyCode; if (key == 8 || key == 46) span.textContent = area.value; }); area.attachEvent("oncut", function() { span.textContent = area.value; }); //处理粘贴 } container.className += "active"; } var areas = document.getElementById('textarea'); makeExpandingArea(areas);

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