使用样式化组件，我想构建一个React组件，该组件将模仿W3学校的以下代码：
ul {
list-style-type: none;
margin: 0;
padding: 0;
overflow: hidden;
background-color: #333;
}
li {
float: left;
}
li a, .dropbtn {
display: inline-block;
color: white;
text-align: center;
padding: 14px 16px;
text-decoration: none;
}
li a:hover, .dropdown:hover .dropbtn {
background-color: red;
}
li.dropdown {
display: inline-block;
}
.dropdown-content {
display: none;
position: absolute;
background-color: #f9f9f9;
min-width: 160px;
box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
z-index: 1;
}
.dropdown-content a {
color: black;
padding: 12px 16px;
text-decoration: none;
display: block;
text-align: left;
}
.dropdown-content a:hover {background-color: #f1f1f1;}
.dropdown:hover .dropdown-content {
display: block;
}<body>
<ul>
<li><a href="#home">Home</a></li>
<li><a href="#news">News</a></li>
<li class="dropdown">
<a href="javascript:void(0)" class="dropbtn">Dropdown</a>
<div class="dropdown-content">
<a href="#">Link 1</a>
<a href="#">Link 2</a>
<a href="#">Link 3</a>
</div>
</li>
</ul>
<h3>Dropdown Menu inside a Navigation Bar</h3>
<p>Hover over the "Dropdown" link to see the dropdown menu.</p>
</body>
</html>这是我的React组件：
import React, { Component } from "react";
import PropTypes from "prop-types";
import styled, { ThemeProvider } from "styled-components";
const StyledUl = styled.ul`
list-style-type: none;
margin: 0;
overflow: hidden;
background-color: #333;
padding: 0px;
background-color: lightblue;
color: black;
font-weight: bold;
`;
const StyledLi = styled.li`
float: left;
height: 100%;
padding: 10px;
&:hover {
background-color: red;
}
`;
const DropDownContent = styled.div`
display: none;
position: absolute;
min-width: 160px;
z-index: 1;
`;
const DropDownLi = styled(StyledLi)`
display: inline-block;
&:hover ${DropDownContent} {
display: block;
}
`;
const StyledA = styled.a`
display: inline-block;
text-align: center;
text-decoration: none;
`;
const SubA = styled(StyledA)`
text-decoration: none;
display: block;
text-align: left;
background-color: lightblue;
padding: 10px;
`;
class Menu extends Component {
handleClick = action => {
if (!action) return;
if (this.props.onClick) this.props.onClick(action);
};
render = () => {
return (
<StyledUl>
<StyledLi>
<StyledA onClick={() => this.handleClick("Home")}>
Home
</StyledA>
</StyledLi>
<StyledLi>
<StyledA onClick={() => this.handleClick("News")}>
Home
</StyledA>
</StyledLi>
<DropDownLi>
<StyledA onClick={() => this.handleClick("DropDown")}>
DropDown
</StyledA>
<DropDownContent>
{" "}
<SubA onClick={() => this.handleClick("Link1")}>
Link 1
</SubA>
<SubA onClick={() => this.handleClick("Link2")}>
Link 2
</SubA>
<SubA onClick={() => this.handleClick("Link3")}>
Link 3
</SubA>
</DropDownContent>
</DropDownLi>
</StyledUl>
);
};
}
export default Menu;
结果不一样，主要是因为我不知道如何在styled-component中使用选择器。
如何修复我的ReactJs组件Menu代码，使其行为与W3示例完全相同？
您在翻译代码时犯了一些小错误，但语法和概念都是正确的。您对选择器的使用是正确的：
/* Hovering over current component */
&:hover {
background-color: red;
}
/* Selecting another styled component */
/* calls DropDownContent.toString(), which returns */
/* the class name of the styled component: .sc-bxivhb */
&:hover ${DropDownContent} {
display: block;
}
这是一个更正的版本：
import React, { Component } from "react";
import styled from "styled-components";
const StyledUl = styled.ul`
list-style-type: none;
margin: 0;
padding: 0;
overflow: hidden;
background-color: #333;
`;
const StyledLi = styled.li`
float: left;
`;
const Dropbtn = styled.div`
display: inline-block;
color: white;
text-align: center;
padding: 14px 16px;
text-decoration: none;
`;
const DropDownContent = styled.div`
display: none;
position: absolute;
background-color: #f9f9f9;
min-width: 160px;
box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
z-index: 1;
`;
const DropDownLi = styled(StyledLi)`
display: inline-block;
&:hover {
background-color: red;
}
&:hover ${DropDownContent} {
display: block;
}
`;
const StyledA = styled.a`
display: inline-block;
color: white;
text-align: center;
padding: 14px 16px;
text-decoration: none;
&:hover {
background-color: red;
}
`;
const SubA = styled.a`
color: black;
padding: 12px 16px;
text-decoration: none;
display: block;
text-align: left;
&:hover {
background-color: #f1f1f1;
}
`;
class Menu extends Component {
handleClick = action => {
if (!action) return;
if (this.props.onClick) this.props.onClick(action);
};
render = () => {
return (
<StyledUl>
<StyledLi>
<StyledA onClick={() => this.handleClick("Home")}>Home</StyledA>
</StyledLi>
<StyledLi>
<StyledA onClick={() => this.handleClick("News")}>Home</StyledA>
</StyledLi>
<DropDownLi>
<Dropbtn onClick={() => this.handleClick("DropDown")}>
DropDown
</Dropbtn>
<DropDownContent>
{" "}
<SubA onClick={() => this.handleClick("Link1")}>Link 1</SubA>
<SubA onClick={() => this.handleClick("Link2")}>Link 2</SubA>
<SubA onClick={() => this.handleClick("Link3")}>Link 3</SubA>
</DropDownContent>
</DropDownLi>
</StyledUl>
);
};
}
export default Menu;
您需要使用类似scss的语法。为了使用像hover这样的伪选择器，您需要进行嵌套并使用与号和(&)，后者将返回到主选择器。如果您愿意，也可以使用常规的class选择器。
您的代码示例：
export const Menu = styled.ul `
/* main UL component called: "Menu" */
list-style-type: none;
margin: 0;
padding: 0;
overflow: hidden;
background-color: #333;
/* main LI */
& > li {
float: left;
& > a {
display: inline-block;
color: white;
text-align: center;
padding: 14px 16px;
text-decoration: none;
&:hover {
background-color: red;
}
}
}
/* dropdown LI */
& > .dropdown {
display: inline-block;
& > .dropdown-content {
display: none;
position: absolute;
background-color: #f9f9f9;
min-width: 160px;
box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
z-index: 1;
& > a {
color: black;
padding: 12px 16px;
text-decoration: none;
display: block;
text-align: left;
&:hover {
background-color: #f1f1f1;
}
}
}
&:hover .dropdown-content {
display: block
}
}
`
对于JSX部分，只需调用菜单组件
<Menu>
<li><a href="#">Home</a></li>
<li><a href="#">News</a></li>
<li className="dropdown">
<a href="#" className="dropbtn">Dropdown</a>
<div className="dropdown-content">
<a href="#">Link 1</a>
<a href="#">Link 2</a>
<a href="#">Link 3</a>
</div>
</li>
</Menu>
这样，我只创建了一个名为Menu的组件，并且所有JSX元素都像普通HTML一样嵌套。
请参阅codesandbox中的完整示例：