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textarea自适应高度,显示滚动条

textarea自适应高度,显示滚动条

作者: 他大舅啊 | 来源:发表于2017-05-31 15:06 被阅读180次

    调用

    autosize(document.querySelectorAll('textarea'));

    /*!

    Autosize 2.0.0

    license: MIT

    textarea根据内容自动延伸,显示滚动条

    */

    (function (root, factory) {

    'use strict';

    if (typeof define === 'function' && define.amd) {

    // AMD. Register as an anonymous module.

    define([], factory);

    } else if (typeof exports === 'object') {

    // Node. Does not work with strict CommonJS, but

    // only CommonJS-like environments that support module.exports,

    // like Node.

    module.exports = factory();

    } else {

    // Browser globals (root is window)

    root.autosize = factory();

    }

    }(this, function () {

    function main(ta) {

    if (!ta || !ta.nodeName || ta.nodeName !== 'TEXTAREA' || ta.hasAttribute('data-autosize-on')) { return; }

    var maxHeight;

    var heightOffset;

    function init() {

    var style = window.getComputedStyle(ta, null);

    if (style.resize === 'vertical') {

    ta.style.resize = 'none';

    } else if (style.resize === 'both') {

    ta.style.resize = 'horizontal';

    }

    // horizontal overflow is hidden, so break-word is necessary for handling words longer than the textarea width

    ta.style.wordWrap = 'break-word';

    // Chrome/Safari-specific fix:

    // When the textarea y-overflow is hidden, Chrome/Safari doesn't reflow the text to account for the space

    // made available by removing the scrollbar. This workaround will cause the text to reflow.

    var width = ta.style.width;

    ta.style.width = '0px';

    // Force reflow:

    /* jshint ignore:start */

    ta.offsetWidth;

    /* jshint ignore:end */

    ta.style.width = width;

    maxHeight = style.maxHeight !== 'none' ? parseFloat(style.maxHeight) : false;

    if (style.boxSizing === 'content-box') {

    heightOffset = -(parseFloat(style.paddingTop)+parseFloat(style.paddingBottom));

    } else {

    heightOffset = parseFloat(style.borderTopWidth)+parseFloat(style.borderBottomWidth);

    }

    adjust();

    }

    function adjust() {

    var startHeight = ta.style.height;

    var htmlTop = document.documentElement.scrollTop;

    var bodyTop = document.body.scrollTop;

    ta.style.height = '16px';

    var endHeight = ta.scrollHeight+heightOffset;

    if (maxHeight !== false && maxHeight < endHeight) {

    endHeight = maxHeight;

    if (ta.style.overflowY !== 'scroll') {

    ta.style.overflowY = 'scroll';

    }

    } else if (ta.style.overflowY !== 'hidden') {

    ta.style.overflowY = 'hidden';

    }

    ta.style.height = endHeight+'px';

    // prevents scroll-position jumping

    document.documentElement.scrollTop = htmlTop;

    document.body.scrollTop = bodyTop;

    if (startHeight !== ta.style.height) {

    var evt = document.createEvent('Event');

    evt.initEvent('autosize.resized', true, false);

    ta.dispatchEvent(evt);

    }

    }

    // IE9 does not fire onpropertychange or oninput for deletions,

    // so binding to onkeyup to catch most of those events.

    // There is no way that I know of to detect something like 'cut' in IE9.

    if ('onpropertychange' in ta && 'oninput' in ta) {

    ta.addEventListener('keyup', adjust);

    }

    window.addEventListener('resize', adjust);

    ta.addEventListener('focus', adjust);

    ta.addEventListener('input', adjust);

    ta.addEventListener('autosize.update', adjust);

    ta.addEventListener('autosize.destroy', function(style){

    window.removeEventListener('resize', adjust);

    ta.removeEventListener('focus', adjust);

    ta.removeEventListener('input', adjust);

    ta.removeEventListener('keyup', adjust);

    ta.removeEventListener('autosize.destroy');

    Object.keys(style).forEach(function(key){

    ta.style[key] = style[key];

    });

    ta.removeAttribute('data-autosize-on');

    }.bind(ta, {

    height: ta.style.height,

    overflow: ta.style.overflow,

    overflowY: ta.style.overflowY,

    wordWrap: ta.style.wordWrap,

    resize: ta.style.resize

    }));

    ta.setAttribute('data-autosize-on', true);

    ta.style.overflow = 'hidden';

    ta.style.overflowY = 'hidden';

    init();

    }

    // Do nothing in IE8 or lower

    if (typeof window.getComputedStyle !== 'function') {

    return function(elements) {

    return elements;

    };

    } else {

    return function(elements) {

    if (elements && elements.length) {

    Array.prototype.forEach.call(elements, main);

    } else if (elements && elements.nodeName) {

    main(elements);

    }

    return elements;

    };

    }

    }));

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