textarea高度自适应

Html

Css

 #textarea {
	font:1.4em/1.8em Arial;
	overflow:hidden;
	width:550px;
	height:6em;
	padding:10px;
}

/**
  * 文本框根据输入内容自适应高度
  * @author                tang bin
  * @version                0.2
  * @param                {HTMLElement}        输入框元素
  * @param                {Number}                设置光标与输入框保持的距离(默认20)
  * @param                {Number}                设置最大高度(可选)
  */
 var autoTextarea = function(elem, extra, maxHeight) {
     extra = extra || 20;
     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();
 };

var text = document.getElementById("textarea"),
     tip = '知道吗..';

autoTextarea(text); // 调用

text.value = tip;

text.onmouseover = function() { 
     if (text.value === tip) text.value = '';
 };
 text.onblur = function() {
     if (text.value === '') text.value = tip;
 };

↑上面代码改变，会自动显示代码结果 jQuery调用版本：1.11.3

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textarea高度自适应



代码描述：文本框textarea根据输入内容行数多少自适应调节高度的

更新时间：2019-09-07 23:29:31
文本框textarea根据输入内容行数多少自适应调节高度的js特效

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2019/9/28 10:34:13

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