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[英]How to fix “Expected an assignment or function call and instead saw an expression” in reactjs?
[英]ReactJS error: “Expected an assignment or function call and instead saw an expression”
我在下面的菜单组件中尝试在以下Map函数中进行重构
当m.menuLabel
等于“ Login”时,我想渲染添加标签<i class="fa fa-fw fa-user"></i>
,但出现错误
“预期了一个赋值或函数调用,而是看到了一个表达式”
import React from 'react';
import { Link } from 'react-router-dom';
const MENUDATA = [
{ menuLink: "/", menuLabel: "Home" },
{ menuLink: "/products", menuLabel: "Products" },
{ menuLink: "/test", menuLabel: "404" },
{ menuLink: "/login", menuLabel: "Login" }
];
function Menu(props) {
return (
<nav class="navbar bg-faded">
<div class="container">
<ul class="navbar-nav mr-auto">
{MENUDATA.map(m => {
if (m.menuLabel == "Login") {
<li class="nav-item active" key={m.menuLabel}>
<Link class="nav-link" to={m.menuLink}>
<i class="fa fa-fw fa-user"></i>
{m.menuLabel}
</Link>
</li>
}
else {
<li class="nav-item active" key={m.menuLabel}>
<Link class="nav-link" to={m.menuLink}>
{m.menuLabel}
</Link>
</li>
}
})}
</ul>
</div>
</nav>
);
}
export default Menu;
您忘记了从地图返回价值
<ul class="navbar-nav mr-auto">
{MENUDATA.map(m => {
if (m.menuLabel == "Login") {
return <li class="nav-item active" key={m.menuLabel}>
<Link class="nav-link" to={m.menuLink}>
<i class="fa fa-fw fa-user"></i>
{m.menuLabel}
</Link>
</li>
}
else {
return <li class="nav-item active" key={m.menuLabel}>
<Link class="nav-link" to={m.menuLink}>
{m.menuLabel}
</Link>
</li>
}
})}
</ul>
您应该使用map方法返回一个jsx元素:
import React from 'react';
import { Link } from 'react-router-dom';
const MENUDATA = [
{ menuLink: "/", menuLabel: "Home" },
{ menuLink: "/products", menuLabel: "Products" },
{ menuLink: "/test", menuLabel: "404" },
{ menuLink: "/login", menuLabel: "Login" }
];
function Menu(props) {
return (
<nav class="navbar bg-faded">
<div class="container">
<ul class="navbar-nav mr-auto">
{MENUDATA.map(m => {
return(m.menuLabel == "Login"?(<li class="nav-item active"
key={m.menuLabel}>
<Link class="nav-link" to={m.menuLink}>
<i class="fa fa-fw fa-user"></i>
{m.menuLabel}
</Link>
</li>)
:(<li class="nav-item active" key={m.menuLabel}>
<Link class="nav-link" to={m.menuLink}>
{m.menuLabel}
</Link>
</li>))
}
)}
</ul>
</div>
</nav>
);
}
export default Menu;
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