项目中需要用到textarea ，而且高度要随输入的内容自适应，网上查了很多资料，发现有两种解决的办法很好用，就摘录下来，方便以后的学习和运用
方法一：使用原声js
demo演示地址:http://www.xuanfengge.com/demo/201308/textarea/demo2.html
<!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>文本框根据输入内容自适应高度</title> <style type="text/css"> h2 { text-align: center; margin: 50px auto; } #textarea { display: block; margin: 0 auto; overflow: hidden; width: 550px; font-size: 14px; height: 18px; line-height: 24px; padding: 2px; } textarea { outline: 0 none; border-color: rgba(82, 168, 236, 0.8); box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.1), 0 0 8px rgba(82, 168, 236, 0.6); } </style> <script> /*** * 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(); }; </script> </head> <body> <h2>文本框根据输入内容自适应高度</h2> <textarea id="textarea" placeholder="回复内容"></textarea> <script> var text = document.getElementById("textarea"); autoTextarea(text); // 调用 </script> </body> </html>
方法二：div模拟textarea文本域轻松实现高度自适应
demo演示地址：http://www.xuanfengge.com/demo/201308/textarea/demo1.html
<!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> <title>div模拟textarea文本域轻松实现高度自适应</title> <style> h2 { text-align: center; margin: 50px auto; } .test_box { width: 400px; min-height: 20px; /*设置最小高度*/ max-height: 1000px; /*设置最大高度超过300px时出现滚动条*/ _height: 120px; margin-left: auto; margin-right: auto; padding: 13px; outline: 0; border: 1px solid #a0b3d6; font-size: 16px; line-height: 24px; word-wrap: break-word; overflow-x: hidden; overflow-y: auto; border-color: rgba(82, 168, 236, 0.8); box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.1), 0 0 8px rgba(82, 168, 236, 0.6); } </style> </head> <body> <h2>div模拟textarea文本域轻松实现高度自适应</h2> <div class="test_box" contenteditable="true"> <br /> </div> </body> </html>