(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 widthta.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 = 'auto';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 jumpingdocument.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('input', adjust);ta.addEventListener('autosize.update', adjust);ta.addEventListener('autosize.destroy', function(style){window.removeEventListener('resize', 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 lowerif (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;};}}));引入上面的js，然后在需要用的页面执行下面这行代码　　autosize(document.querySelectorAll('textarea'));