Javascript ReactJS错误：“引用；应为赋值或函数调用，而应为表达式；

我有下面的菜单组件，我正试图在下面的映射函数中重构它

当

m.menuLabel

等于“Login”时，我想渲染添加标记

，但我得到以下错误

“应为赋值或函数调用，而应为表达式”

从“React”导入React；
从'react router dom'导入{Link}；
常数MENUDATA=[
{menuLink:“/”，menuLabel:“Home”}，
{menuLink:“/products”，menuLabel:“products”}，
{menuLink:“/test”，menuLabel:“404”}，
{menuLink:“/login”，menuLabel:“login”}
];
功能菜单（道具）{
返回(

{MENUDATA.map（m=>{
如果（m.menuLabel==“登录”）{

{m.menuLabel}

}
否则{

{m.menuLabel}

}
})}

);
}
导出默认菜单；

您忘记了从映射返回值

<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>

{MENUDATA.map（m=>{
如果（m.menuLabel==“登录”）{
return

{m.menuLabel}

}
否则{
return

{m.menuLabel}

}
})}

您应该使用map方法返回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;

从“React”导入React；
从'react router dom'导入{Link}；
常数MENUDATA=[
{menuLink:“/”，menuLabel:“Home”}，
{menuLink:“/products”，menuLabel:“products”}，
{menuLink:“/test”，menuLabel:“404”}，
{menuLink:“/login”，menuLabel:“login”}
];
功能菜单（道具）{
返回(

{MENUDATA.map（m=>{
返回（m.menuLabel==“登录”？（

{m.menuLabel}
）
：（

{m.menuLabel}
））
}
)}

);
}
导出默认菜单；

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;