react js中的多级下拉菜单不可用，还是什么？就像react-bootstrap

Question

我正在使用下面的代码

import Navbar from 'react-bootstrap/Navbar';
import Nav from 'react-bootstrap/Nav';
import NavDropdown from 'react-bootstrap/NavDropdown'

但是我找不到像这样的多级下拉菜单

My-Menu
       menu-1
             menu-1-a
             menu-1-b   
       menu-2
       menu-3
            menu-3-a
            menu-3-b

在“react-bootstrap”中有可以使用的多级下拉菜单吗？

Answer 1

这就是你要找的吗？http://jsfiddle.net/n5u2wwjg/233886/

​

class DropdownMenu extends React.Component {

  getMenuItemTitle = (menuItem, index, depthLevel) => {
    return menuItem.title;
  };
 
  getMenuItem = (menuItem, depthLevel, index) => {
    let title = this.getMenuItemTitle(menuItem, index, depthLevel);

    if (menuItem.submenu && menuItem.submenu.length > 0) {
      return (
        <li>
          {title}
          <DropdownMenu config={menuItem.submenu} submenu={true} />
        </li>
      );
    } else {
      return <li>{title}</li>;
    }
  };

  render = () => {
    let { config } = this.props;

    let options = [];
    config.map((item, index) => {
      options.push(this.getMenuItem(item, 0, index));
    });

    if (this.props.submenu && this.props.submenu === true)
      return <ul>{options}</ul>;

    return <ul className="dropdown-menu">{options}</ul>;
  };
}


ReactDOM.render(<DropdownMenu config={[
    {
      "title": "Option 1",
      "submenu": null
    },
    {
      "title": "Option 2",
      "submenu": [
        {
          "title": "Option 2.1",
          "submenu": [
            {
              "title": "Option 2.1.1",
              "submenu": null
            },
            {
              "title": "Option 2.1.2",
              "submenu": null
            }
          ]
        },
        {
          "title": "Option 2.2",
          "submenu": [
            {
              "title": "Option 2.2.1",
              "submenu": null
            },
            {
              "title": "Option 2.2.2",
              "submenu": null
            }
          ]
        }
      ]
    }
  ]}/>, document.querySelector("#app"))

.dropdown-menu {
  height: 35px;
  list-style: none;
  margin: 0;
  padding: 0;
  float: left;
  text-align: center;
}

.dropdown-menu li {
  display: inline-block;
  position: relative;
  float: left;
  width: 200px;
  line-height: 35px;
  text-decoration: none;
}

.dropdown-menu li li a {
  font-size: 12px;
}

.dropdown-menu li:hover {
  background: blue;
}


/*--- Sublist Styles ---*/

.dropdown-menu ul {
  position: absolute;
  display: none;
}


/*--- Hide Sub Sublists ---*/

.dropdown-menu li:hover ul ul {
  display: none;
}


/*--- Sublevel UL's display and position on hover ---*/

.dropdown-menu li:hover ul {
  display: block;
}

.dropdown-menu li li:hover ul {
  margin-left: 200px;
  /*This must be width of menu box*/
  margin-top: -35px;
  display: block;
}

nu-li {
  padding: 10px;
}

.dropdown-submenu {
  position: absolute;
  left: 0px;
  top: 0px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.3.1/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.3.1/umd/react-dom.production.min.js"></script>
<div id="app"></div>

​

Answer 2

它可以使用以下方法来实现：

1. recursiveMenu:嵌入下拉列表menu
2. CustomToggle:模拟原始的下拉列表项目
3. render:遍历项目数组：

​

export const data = [
  {
    "_class": "leaf",
    "name": "Node"
  },
  {
    "_class": "submenu",
    "name": "Submenu",
    "children": [
      {
        "_class": "leaf",
        "name": "Node"
      },
      {
        "_class": "leaf",
        "name": "Node"
      }
    ]
  }
]

​

​

  const recursiveMenu = (items, parent='') => {
    return (
      items.map(
        (o, i) => o._class !== 'submenu' ? (
          <Dropdown.Item key={`${i}/${o.name}`} onSelect={props.onSelect} id={`${parent}/${o.name}`}>{o.name}</Dropdown.Item>
        ) : o.children?.length > 0 ? (
          <Dropdown key={i} drop='right'>
            <Dropdown.Toggle as={CustomToggle} id="dropdown-basic">
              {o.name}
            </Dropdown.Toggle>
            <Dropdown.Menu>
              {recursiveMenu(o.children, `${parent}/${o.name}`)}
            </Dropdown.Menu>
          </Dropdown>
          ) : null
      )
    )
  }

  const CustomToggle = React.forwardRef(({ children, onClick }, ref) => (
    <a
      className="dropdown-item dropdown-toggle"
      href=""
      ref={ref}
      onMouseEnter={(e) => onClick(e)}
      onClick={(e) => {
        e.preventDefault();
        onClick(e);
      }}
    >
      {children}
    </a>
  ));

  return (
    <Dropdown ref={ref}>
      <Dropdown.Toggle variant="success" id="dropdown-basic">
        {props.dataValue}
      </Dropdown.Toggle>
      <Dropdown.Menu>
        {recursiveMenu(data)}
      </Dropdown.Menu>
    </Dropdown>
  )

​

Answer 3

你可以使用一些包来实现这一点，希望它可以帮助某人在react中使用https://github.com/SUPPLYcom/react-mega-menu这个包进行多层次的下拉。

import ReactMegaMenu from "react-mega-menu"

<ReactMegaMenu 
   tolerance={50}      // optional, defaults to 100
   direction={"LEFT"}  
   styleConfig={...}  
   onExit={()=>{...}}
   data={[
  {
     label: "Category1",
     key: "Category1",
     items: "Category1 content"
  },
  {
     label: "Category2",
     key: "Category2",
     items: "Category2 content"
  },
  {
     label: "Category3",
     key: "Category3",
     items: "Category3 content"
   }
 ]}        // array of data to be rendered
/>

演示应该是这样的-

​

​

最终输出可能如下所示的

​

​

希望，这能帮助一些人。