vue中textarea标签自适应高度

textarea.js文件

/**

                * 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)

                */

export default 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();
};

该文件是操作DOM元素，可以使用vue的自定义指令，方便使用

创建directives.js 文件用来放自定义指令

import Vue from 'vue'
import autoTextarea from './assets/lib/textarea'

Vue.directive('growHeight', {
    componentUpdated: function (el,bonding) {
        const grow = el.getAttribute('data-grow');
        if (grow==='false'){
            autoTextarea(el, bonding.value);
            el.setAttribute('data-grow','true');
        }
    },
    inserted: function (el) {
        el.setAttribute('data-grow','false');
    }
});

如果DOM绑定数据，当第一次改变绑定的数据时，才调用autoTextarea事件

使用

<textarea v-grow-height="60" id="textarea" maxlength="500" placeholder="请输入作品描述，不超过500字"
                      v-model="data"></textarea>

样式自己修改

#textarea {
        display: block;
        width: 676px;
        border: 0;
        margin-left: 10px;
        font-size: 15px;
        outline: none;
        border-radius: 5px;
        padding: 14px;
        background-color: #efe9db;
        word-break: break-all;
        min-height: 100px;
    }

    textarea {
        outline: 0 none;
    }