Question

我有一个对象数组，其中包含导航栏的密钥对值链接，我已将数组映射到列表并成功渲染，但是当我尝试将类添加到仅活动链接时，它正在添加类所有链接项。

想知道我要去哪里错了吗？

import React, { Component } from "react";
import { Link } from "react-router-dom";

class SideNavbar extends Component {
  constructor(props) {
    super(props);
    this.state = [
      { id: 1, name: "Link1", to: "/cms", className: "side_nav_item" },
      { id: 2, name: "Link2", to: "/cms", className: "side_nav_item" },
      { id: 3, name: "Link3", to: "/cms", className: "side_nav_item" },
      { id: 4, name: "Link4", to: "/cms", className: "side_nav_item" }
    ];
  }

  handleClick = () => {
    const currentClass = document.getElementsByClassName("side_nav_item");
    for (let i = 0; i < currentClass.length; i++) {
      currentClass[i].classList.toggle("active_item");
      console.log(currentClass[i]);
    }
  };
  render() {
    const navLinks = this.state.map(link => {
      return (
        <div key={link.id}>
          <ul>
            <li onClick={this.handleClick} className={link.className}>
              <Link to={link.to}>{link.name}</Link>
            </li>
          </ul>
        </div>
      );
    });
    return <div>{navLinks}</div>;
  }
}

export default SideNavbar;

Answer 1

您可以保留一个状态，例如： activeLink存储活动链接的ID，您可以使用该ID将类应用于render方法中的活动链接。

示例

class SideNavbar extends React.Component {
  state = {
    links: [
      {
        id: 1,
        name: "Link1",
        to: "/cms",
        className: "side_nav_item"
      },
      {
        id: 2,
        name: "Link2",
        to: "/cms",
        className: "side_nav_item"
      },
      {
        id: 3,
        name: "Link3",
        to: "/cms",
        className: "side_nav_item"
      },
      {
        id: 4,
        name: "Link4",
        to: "/cms",
        className: "side_nav_item"
      }
    ],
    activeLink: null
  };

  handleClick = id => {
    this.setState({ activeLink: id });
  };

  render() {
    const { links, activeLink } = this.state;

    return (
      <div>
        {links.map(link => {
          return (
            <div key={link.id}>
              <ul>
                <li
                  onClick={() => this.handleClick(link.id)}
                  className={
                    link.className +
                    (link.id === activeLink ? " active_item" : "")
                  }
                >
                  {link.name} {link.id === activeLink && "active!"}
                </li>
              </ul>
            </div>
          );
        })}
      </div>
    );
  }
}

ReactDOM.render(<SideNavbar />, document.getElementById("root"));

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>

<div id="root"></div>

Answer 2

问题是这行代码：
const currentClass = document.getElementsByClassName('side_nav_item');

正在使用HTML CSS类抓取您所有的side_nav_items元素，在您的情况下，这就是您所有的侧面导航链接。您可能要使用：

let element = document.getElementById(id);

只是获得由id标识的被单击的侧面导航元素。然后，您可以使用element.classList.add('active_item');将active_item css类添加到所选的侧面导航项。

希望有帮助！

如何在ReactJS中向单击的项目添加活动类

2 个答案: