我是Reactjs的新手,我想了解如何在Reactjs样式组件中重现此jquery示例:事件“滚动”时模糊背景图像https://jsfiddle.net/BinaryMoon/8jhw2/
$(document).ready(function() {
$(window).scroll(function(e) {
var s = $(window).scrollTop(),
opacityVal = (s / 200);
$('.blurred-image').css('opacity', opacityVal);
});
});
.img-src {
position: absolute;
background:url(http://bromleydemo.files.wordpress.com/2013/10/blossom.jpg?w=600) center center;
background-size: cover;
}
如您所见,背景网址已设置为CSS道具我已经在reactjs中尝试过一些东西,但是每次滚动时,都会重新加载图像背景。有人可以帮我吗?
ps:如果可以使用样式化组件来实现该解决方案,那就太好了
ps2:这是我要实现的效果的另一页https://codepen.io/zrichard/pen/wEFBd
谢谢
您可以使用the useEffect hook将事件侦听器绑定到窗口。
import React, { useState, useEffect } from "react";
import styled, { css } from "styled-components";
import { hydrate, render } from "react-dom";
function App() {
const [opacity, setOpacity] = useState(0);
useEffect(() => {
const onScroll = () => setOpacity(window.scrollY / 200);
window.addEventListener("scroll", onScroll);
return function cleanup() {
window.removeEventListener("scroll", onScroll);
};
}, []);
return (
<React.Fragment>
<BlurredImageContainer>
<ImgSrc />
<ImgSrc blurred opacity={opacity} />
</BlurredImageContainer>
<Content>
<Avatar src="https://pbs.twimg.com/profile_images/378800000748837969/bd8e553e5cae83ef488c6b15166bdd55.png" />
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
<p>This is some test content</p>
</Content>
</React.Fragment>
);
}
const BlurredImageContainer = styled.div`
display: block;
padding: 0;
position: fixed;
top: 0;
bottom: 0;
left: 0;
right: 0;
z-index: -1;
`;
const ImgSrc = styled.div`
position: absolute;
background: url("http://bromleydemo.files.wordpress.com/2013/10/blossom.jpg?w=600") center center;
background-size: cover;
top: -10%;
bottom: 10%;
left: -10%;
right: 10%;
width: 120%;
height: 120%;
${props => props.blurred && css`
opacity: ${props.opacity};
filter: blur(20px) brightness(0.7);
`};
`;
const Content = styled.div`
padding: 150px 50px;
color: #fff;
text-align: center;
`;
const Avatar = styled.div`
height: 120px;
width: 120px;
border-radius: 100%;
border: 5px solid #fff;
margin: 0 auto 50px;
`;
const rootElement = document.getElementById("root");
if (rootElement.hasChildNodes()) {
hydrate(<App />, rootElement);
} else {
render(<App />, rootElement);
}