Toggle dropdown menu in reactjs

问题:

I have the following code for a simple dropdown menu on my navbar: https://jsfiddle.net/jL3yyk98/10/

index.html

<div id="menu-button"></div>

NavMenu.js

var NavMenu = React.createClass({
    getDefaultProps: function()
    {
        return {
            isOpen: false
        };
    },

    render: function()
    {
        if (this.props.isOpen)
        {
            return (
                <div className="dropdown">
                    <ul>
                        <li><a href="#">News</a></li>
                        <li><a href="#">About</a></li>
                        <li><a href="#">Guidelines</a></li>
                        <li><a href="#">Exchange</a></li>
                        <li><a href="#">Forum</a></li>
                    </ul>
                </div>
            );
        }
        return null;
    }
});

NavMenuButton.js

var NavMenuButton = React.createClass({

    getInitialState: function()
    {
        return {
            isOpen: false
        };
    },

    toggleMenu: function(e)
    {
        e.stopPropagation();
        this.setState({isOpen: !this.state.isOpen});
    },

    onClose: function()
    {
        this.setState({isOpen: false});
    },

    componentDidMount: function ()
    {
        document.body.addEventListener('click', this.onClose);
    },

    componentWillUnmount: function ()
    {
        document.body.removeEventListener('click', this.onClose);
    },

    render: function()
    {
        return (
            <div>
                <a onClick={this.toggleMenu} href="#">Menu</a>
                <NavMenu isOpen={this.state.isOpen} />
            </div>
        );
    }

});

React.render(<NavMenuButton />, document.getElementById('menu-button'));

I understand with my current code that both the toggleMenu method and onClose method are called when the user clicks the menu button to close the menu (since they are also effectively clicking the body); and that the onClose method is called first, meaning that the state is set to false, but then the toggleMenu method is called and it's set back to true. Why is this, and how can I fix it so that clicking the menu button toggles the menu and clicking the body hides the menu?

If this approach seems wrong what approach should I be using? I'm fairly new to react so I'm still learning what goes where and why.

Also, I cannot use a full body div as the solution to this, it needs to be a typical dropdown; so if users want to interact with another part of the page (maybe clicking a link), then they can do that.

回答1:

Your issue is that clicking on the link will also call the body click listener. It means that your state will go from:

1. Click on link
2. Click listener on body called
3. This.state.open set to false
4. Render called with this.state.open false
5. Click listener on the link called
6. This.state.open set to true
7. Render called with this.state.open true

e.stopPropagation() doesn't work in React. One workaround would be to:

handleBodyClick: function(e)
{
    if (e.target.nodeName !== 'A') {
       this.setState({isOpen: false});
    }
},

Another way (and better way) would be to have the click listener not on body, but on a div, and make it as big as possible (to be as the same size a body basically).

Here is an example with binding a click on a div instead of body: https://jsfiddle.net/jL3yyk98/

回答2:

handleClose: function() {
  this.setState({isOpen: false});
},

handleGlobalClick: function(event) {
  var _con = this.refs.mC.getDOMNode() // <component ref="mC">
  if (!(_con == event.target) && !_con.contains(event.target)) {
    this.handleClose();
  }
},

componentDidMount: function() {
  document.body.addEventListener('click', this.handleGlobalClick);
},

componentWillUnmount: function() {
  document.body.removeEventListener('click', this.handleGlobalClick);
},

this work on the latest chrome, you can also use the jQuery rewrite the node.contains()