css部分
#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(0,0.1),0 0 8px rgba(82,0.6); }
js代码
/** * 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(); };
html部分 包含调用