textarea如何实现高度自适应 #112

Seasons123 · 2019-12-25T02:44:37Z

今天需要些一个回复评论的页面，设计师给的初始界面就是一个只有一行的框。然后当时就想这个交互该怎么实现比较好，然后想起了新浪微博的做法：点击评论，默认显示一行，当输入的文字超过一行或者输入Enter时，输入框的高度会随着改变，直到输入完毕。顿时觉得这个细节做得挺不错的，可以效仿下。下面分享2种实现textarea高度自适应的做法，一种是利用JS控制的（因为存在浏览器兼容问题，所以写起来比较麻烦）；另一种是用div来模拟textarea来实现的，用CSS控制样式，不用JS；

Seasons123 · 2019-12-25T02:45:12Z

1.方法一：利用JS控制

<!DOCTYPE html> 
<html xmlns="http://www.w3.org/1999/xhtml" > 
<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>

Seasons123 · 2019-12-25T02:47:26Z

2.方法二：div模拟textarea文本
附上张鑫旭大神的这篇文章： div模拟textarea文本域轻松实现高度自适应
因为textarea不支持自适应高度，就是定好高度或者是行数之后，超出部分就会显示滚动条，看起来不美观。而用DIV来模拟时，首先遇到的问题是：div怎么实现输入功能？可能我们还是第一次见到这个属性contenteditable，如一个普通的block元素上加个contenteditable="true"就实现编辑，出现光标了。
CSS代码：

.test_box {
    width: 400px; 
    min-height: 120px; 
    max-height: 300px;
    _height: 120px; 
    margin-left: auto; 
    margin-right: auto; 
    padding: 3px; 
    outline: 0; 
    border: 1px solid #a0b3d6; 
    font-size: 12px; 
    word-wrap: break-word;
    overflow-x: hidden;
    overflow-y: auto;
    -webkit-user-modify: read-write-plaintext-only;
}

HTML代码：
<div class="test_box" contenteditable="true"><br /></div>
JS代码：

if (typeof document.webkitHidden == "undefined") {
    // 非chrome浏览器阻止粘贴
    box.onpaste = function() {
        return false;
    }
}

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

textarea如何实现高度自适应 #112

textarea如何实现高度自适应 #112

Seasons123 commented Dec 25, 2019 •

edited

Loading

Seasons123 commented Dec 25, 2019

Seasons123 commented Dec 25, 2019 •

edited

Loading

textarea如何实现高度自适应 #112

textarea如何实现高度自适应 #112

Comments

Seasons123 commented Dec 25, 2019 • edited Loading

Seasons123 commented Dec 25, 2019

Seasons123 commented Dec 25, 2019 • edited Loading

Seasons123 commented Dec 25, 2019 •

edited

Loading

Seasons123 commented Dec 25, 2019 •

edited

Loading