Dropdown in React using bootstrap 4

Question

When I click on a single dropdown menu link in the navigation bar, all the dropdown menu links also show or display. How do I fix this by letting only one dropdown menu link show?

I have tried changing the id value that points to aria-labelledby

This is the state of my app

      state = {
        dropDown: false
      };


      handleDropdown = e => {
            this.setState({ dropDown: !this.state.dropDown });
        };

Inside the render function

      render() {
        const { dropDown } = this.state;

      /*Conditional statement to select a class base on the state*/

      const dropMenu = dropDown ? 'dropdown-menu show' : 'dropdown-menu';

      /*The two dropdown menu list the displays(both) even when one is clicked*/

    <li className="nav-item dropdown">
                      <Link
                        onClick={this.handleDropdown}
                        className="nav-link dropdown-toggle"
                        href="#"
                        id="navbarDropdown"
                        role="button"
                        data-toggle="dropdown"
                        aria-haspopup="true"
                        aria-expanded="false"
                      >
                        Dropdown
                      </Link>
                      <div className={dropMenu} aria-labelledby="navbarDropdown">
                        <Link className="dropdown-item" to="#">
                          Action
                        </Link>
                        <Link className="dropdown-item" to="#">
                          Another action
                        </Link>
                        <div className="dropdown-divider" />
                        <Link className="dropdown-item" to="#">
                          Something else here
                        </Link>
                      </div>
                    </li>

    <li className="nav-item dropdown">
                      <Link
                        onClick={this.handleDropdown}
                        className="nav-link dropdown-toggle"
                        href="#"
                        id="navbarDropdown"
                        role="button"
                        data-toggle="dropdown"
                        aria-haspopup="true"
                        aria-expanded="false"
                      >
                        Dropdown
                      </Link>
                      <div className={dropMenu} aria-labelledby="navbarDropdown">
                        <Link className="dropdown-item" to="#">
                          Action
                        </Link>
                        <Link className="dropdown-item" to="#">
                          Another action
                        </Link>
                        <div className="dropdown-divider" />
                        <Link className="dropdown-item" to="#">
                          Something else here
                        </Link>
                      </div>
                    </li>
      };

Answer 1

because you only 1 state to handle show and hide the dropdown menu. try doing it like this :

state = {
  dropDown: {
    link1: false,
    link2: false,
  }
}

handleDropdown = e => {
  const { id } = e.target;

  this.setState(prevState => ({
    dropDown : {
      ...prevState.dropDown,
      [id]: !prevState.dropDown[id],
    }
  }));
}

render() {

const { dropDown } = this.state;

      /*Conditional statement to select a class base on the state*/

      const dropMenu = dropDown ? 'dropdown-menu show' : 'dropdown-menu';

      /*The two dropdown menu list the displays(both) even when one is clicked*/

    <li className="nav-item dropdown">
                      <Link
                        onClick={this.handleDropdown}
                        className="nav-link dropdown-toggle"
                        href="#"
                        id="link1" // name your id same as the variable from state dropDown
                        role="button"
                        data-toggle="dropdown"
                        aria-haspopup="true"
                        aria-expanded="false"
                      >
                        Dropdown
                      </Link>
                      <div className={`dropdown-menu ${dropDown.link1 ? 'show' : ''}`} aria-labelledby="navbarDropdown">
                        <Link className="dropdown-item" to="#">
                          Action
                        </Link>
                        <Link className="dropdown-item" to="#">
                          Another action
                        </Link>
                        <div className="dropdown-divider" />
                        <Link className="dropdown-item" to="#">
                          Something else here
                        </Link>
                      </div>
                    </li>

    <li className="nav-item dropdown">
                      <Link
                        onClick={this.handleDropdown}
                        className="nav-link dropdown-toggle"
                        href="#"
                        id="link2" // name your id same as the variable from state dropDown
                        role="button"
                        data-toggle="dropdown"
                        aria-haspopup="true"
                        aria-expanded="false"
                      >
                        Dropdown
                      </Link>
                      <div className={`dropdown-menu ${dropDown.link2 ? 'show' : ''}`} aria-labelledby="navbarDropdown">
                        <Link className="dropdown-item" to="#">
                          Action
                        </Link>
                        <Link className="dropdown-item" to="#">
                          Another action
                        </Link>
                        <div className="dropdown-divider" />
                        <Link className="dropdown-item" to="#">
                          Something else here
                        </Link>
                      </div>
                    </li>
}

hope it works.

Answer 2

Updated code

Change the state variable as follows:

state = {
  dropDownState: [false, false]
};

As you have just have two li > div the array contains two elements, if menu items increase, increase them as well.

Then the div's would look like

<div className={dropMenu[0]} aria-labelledby="navbarDropdown"> and <div className={dropMenu[1]} aria-labelledby="navbarDropdown">

Each of the function bindings would look like

onClick={() => this.handleDropdown(0)}
onClick={() => this.handleDropdown(1)}

The actual function would then change to

handleDropdown = (menuIndex) => {
   let newMenuState = this.state.dropDownState.map((val, index) => {
       if(index === menuIndex) {
           return !val
       } else return val
   });

  this.setState({ dropDownState: newMenuState })
};

Please note I haven't run the code on my end, but you should get the idea.

Old Answer

Instead of calling the function, bind the value to the function:

Change

onClick={this.handleDropdown}

To

onClick={() => this.handleDropdown()}