React event onMouseLeave not triggered when moving cursor fast

Question

Im trying to implement hover event but onMouseLeave is not always triggering when leaving element especially when moving cursor over elements fast. I tried i Chrome, Firefox and Internet Explorer but in every browser same problem appeared.

My code:

import React from 'react';
import Autolinker from 'autolinker';
import DateTime from './DateTime.jsx'
class Comment extends React.Component{

     constructor(props){
        super(props);
        this.handleOnMouseOver = this.handleOnMouseOver.bind(this);
        this.handleOnMouseOut = this.handleOnMouseOut.bind(this);
        this.state = {
            hovering: false
        };
    }

    render(){
        return <li className="media comment" onMouseEnter={this.handleOnMouseOver} onMouseLeave={this.handleOnMouseOut}>
            <div className="image">
                <img src={this.props.activity.user.avatar.small_url} width="42" height="42" />
            </div>
            <div className="body">
                {this.state.hovering ? null : <time className="pull-right"><DateTime timeInMiliseconds={this.props.activity.published_at} byDay={true}/></time>}
                <p>
                    <strong>
                        <span>{this.props.activity.user.full_name}</span>
                        {this.state.hovering ? <span className="edit-comment">Edit</span> : null}

                    </strong>
                </p>    
             </div>
        </li>;
    }


    handleOnMouseOver(event){
         event.preventDefault();
         this.setState({hovering:true});
    }

    handleOnMouseOut(event){
        event.preventDefault();
        this.setState({hovering:false});
    }

     newlines(text) {
        if (text) 
            return text.replace(/\n/g, '<br />');

    }



}

export default Comment;

Answer 1

seems to be an issue caused by event delegation when the event listener is on the parent element and child elements are being conditionally added/removed from the DOM. putting a "hover target" component that sits on top of everything should make this work properly, but could cause other issues if you need to click elements inside.

<Container isOpen={this.state.isOpen}>
 <HoverTarget
  onMouseEnter={e => this.mouseOver(e)}
  onMouseLeave={e => this.mouseOut(e)}
 />
 <Content/>
</Container>



mouseOver(e) {
  if (!this.state.isOpen) {
    this.setState({ isOpen: true });
  }
}