https://readli.net/js/autogrow.js

1!function(e,t){if("function"==typeof define&&define.amd)define(["exports","module"],t);else if("undefined"!=typeof exports&&"undefined"!=typeof module)t(exports,module);else{var n={exports:{}};t(n.exports,n),e.autosize=n.exports}}(this,function(e,t){"use strict";var n,o,r="function"==typeof Map?new Map:(n=[],o=[],{has:function(e){return n.indexOf(e)>-1},get:function(e){return o[n.indexOf(e)]},set:function(e,t){-1===n.indexOf(e)&&(n.push(e),o.push(t))},delete:function(e){var t=n.indexOf(e);t>-1&&(n.splice(t,1),o.splice(t,1))}}),i=function(e){return new Event(e,{bubbles:!0})};try{new Event("test")}catch(e){i=function(e){var t=document.createEvent("Event");return t.initEvent(e,!0,!1),t}}function d(e){if(e&&e.nodeName&&"TEXTAREA"===e.nodeName&&!r.has(e)){var t,n=null,o=e.clientWidth,d=null,l=function(){e.clientWidth!==o&&p()},s=function(t){window.removeEventListener("resize",l,!1),e.removeEventListener("input",p,!1),e.removeEventListener("keyup",p,!1),e.removeEventListener("autosize:destroy",s,!1),e.removeEventListener("autosize:update",p,!1),Object.keys(t).forEach(function(n){e.style[n]=t[n]}),r.delete(e)}.bind(e,{height:e.style.height,resize:e.style.resize,overflowY:e.style.overflowY,overflowX:e.style.overflowX,wordWrap:e.style.wordWrap});e.addEventListener("autosize:destroy",s,!1),"onpropertychange"in e&&"oninput"in e&&e.addEventListener("keyup",p,!1),window.addEventListener("resize",l,!1),e.addEventListener("input",p,!1),e.addEventListener("autosize:update",p,!1),e.style.overflowX="hidden",e.style.wordWrap="break-word",r.set(e,{destroy:s,update:p}),"vertical"===(t=window.getComputedStyle(e,null)).resize?e.style.resize="none":"both"===t.resize&&(e.style.resize="horizontal"),n="content-box"===t.boxSizing?-(parseFloat(t.paddingTop)+parseFloat(t.paddingBottom)):parseFloat(t.borderTopWidth)+parseFloat(t.borderBottomWidth),isNaN(n)&&(n=0),p()}function u(t){var n=e.style.width;e.style.width="0px",e.offsetWidth,e.style.width=n,e.style.overflowY=t}function a(){var t=e.style.height,r=function(e){for(var t=[];e&&e.parentNode&&e.parentNode instanceof Element;)e.parentNode.scrollTop&&t.push({node:e.parentNode,scrollTop:e.parentNode.scrollTop}),e=e.parentNode;return t}(e),i=document.documentElement&&document.documentElement.scrollTop;e.style.height="";var d=e.scrollHeight+n;0!==e.scrollHeight?(e.style.height=d+"px",o=e.clientWidth,r.forEach(function(e){e.node.scrollTop=e.scrollTop}),i&&(document.documentElement.scrollTop=i)):e.style.height=t}function p(){a();var t=Math.round(parseFloat(e.style.height)),n=window.getComputedStyle(e,null),o="content-box"===n.boxSizing?Math.round(parseFloat(n.height)):e.offsetHeight;if(o!==t?"hidden"===n.overflowY&&(u("scroll"),a(),o="content-box"===n.boxSizing?Math.round(parseFloat(window.getComputedStyle(e,null).height)):e.offsetHeight):"hidden"!==n.overflowY&&(u("hidden"),a(),o="content-box"===n.boxSizing?Math.round(parseFloat(window.getComputedStyle(e,null).height)):e.offsetHeight),d!==o){d=o;var r=i("autosize:resized");try{e.dispatchEvent(r)}catch(e){}}}}function l(e){var t=r.get(e);t&&t.destroy()}function s(e){var t=r.get(e);t&&t.update()}var u=null;"undefined"==typeof window||"function"!=typeof window.getComputedStyle?((u=function(e){return e}).destroy=function(e){return e},u.update=function(e){return e}):((u=function(e,t){return e&&Array.prototype.forEach.call(e.length?e:[e],function(e){return d(e)}),e}).destroy=function(e){return e&&Array.prototype.forEach.call(e.length?e:[e],l),e},u.update=function(e){return e&&Array.prototype.forEach.call(e.length?e:[e],s),e}),t.exports=u});