How do you Hover in ReactJS? - onMouseLeave not re

Question

How can you achieve either a hover event or active event in ReactJS when you do inline styling?

I've found that the onMouseEnter, onMouseLeave approach is buggy, so hoping there is another way to do it.

Specifically, if you mouse over a component very quickly, only the onMouseEnter event is registered. The onMouseLeave never fires, and thus can't update state... leaving the component to appear as if it still is being hovered over. I've noticed the same thing if you try and mimic the ":active" css pseudo-class. If you click really fast, only the onMouseDown event will register. The onMouseUp event will be ignored... leaving the component appearing active.

Here is a JSFiddle showing the problem: https://jsfiddle.net/y9swecyu/5/

Video of JSFiddle with problem: https://vid.me/ZJEO

The code:

var Hover = React.createClass({
    getInitialState: function() {
        return {
            hover: false
        };
    },
    onMouseEnterHandler: function() {
        this.setState({
            hover: true
        });
        console.log('enter');
    },
    onMouseLeaveHandler: function() {
        this.setState({
            hover: false
        });
        console.log('leave');
    },
    render: function() {
        var inner = normal;
        if(this.state.hover) {
            inner = hover;
        }

        return (
            <div style={outer}>
                <div style={inner}
                    onMouseEnter={this.onMouseEnterHandler}
                    onMouseLeave={this.onMouseLeaveHandler} >
                    {this.props.children}
                </div>
            </div>
        );
    }
});

var outer = {
    height: '120px',
    width: '200px',
    margin: '100px',
    backgroundColor: 'green',
    cursor: 'pointer',
    position: 'relative'
}

var normal = {
    position: 'absolute',
    top: 0,
    bottom: 0,
    left: 0,
    right: 0,
    backgroundColor: 'red',
    opacity: 0
}

var hover = {
    position: 'absolute',
    top: 0,
    bottom: 0,
    left: 0,
    right: 0,
    backgroundColor: 'red',
    opacity: 1
}

React.render(
    <Hover></Hover>,         
    document.getElementById('container')
)

Answer 1

You can't with inline styling alone. Do not recommend reimplementing CSS features in JavaScript we already have a language that is extremely powerful and incredibly fast built for this use case -- CSS. So use it! Made Style It to assist.

npm install style-it --save

Functional Syntax (JSFIDDLE)

import React from 'react';
import Style from 'style-it';

class Intro extends React.Component {
  render() {
    return Style.it(`
      .intro:hover {
        color: red;
      }

    `,
      <p className="intro">CSS-in-JS made simple -- just Style It.</p>
    );
  }
}

export default Intro;

JSX Syntax (JSFIDDLE)

import React from 'react';
import Style from 'style-it';

class Intro extends React.Component {
  render() {
    return (
      <Style>
      {`
        .intro:hover {
          color: red;
        }
      `}

      <p className="intro">CSS-in-JS made simple -- just Style It.</p>
    </Style>
  }
}

export default Intro;

Answer 2

I could suggest you an example that was easy for me to understand, I use emotion in React JS to give styles. Here you could find more information of it https://emotion.sh/docs/introduction hope this help you.

const secondStyle = css`
  background: blue;
  height: 20px;
  width: 20px;
  :hover {
    cursor: pointer;
    background: red;
`

function myComponent() {
  return (
     <div className={firstStyle}>
       <button className={secondStyle}>Submit<button>
  )
}

Answer 3

I personally use Style It for inline-style in React or keep my style separately in a CSS or SASS file...

But if you are really interested doing it inline, look at the library, I share some of the usages below:

In the component:

import React from 'react';
import Style from 'style-it';

class Intro extends React.Component {
  render() {
    return (
      <Style>
        {`
          .intro {
            font-size: 40px;
          }
        `}

        <p className="intro">CSS-in-JS made simple -- just Style It.</p>
      </Style>
    );
  }
}

export default Intro;

Output:

    <p class="intro _scoped-1">
      <style type="text/css">
        ._scoped-1.intro {
          font-size: 40px;
        }
      </style>

      CSS-in-JS made simple -- just Style It.
    </p>

Also you can use JavaScript variables with hover in your CSS as below :

import React from 'react';
import Style from 'style-it';

class Intro extends React.Component {
  render() {
    const fontSize = 13;

    return Style.it(`
      .intro {
        font-size: ${ fontSize }px;  // ES2015 & ES6 Template Literal string interpolation
      }
      .package {
        color: blue;
      }
      .package:hover {
        color: aqua;
      }
    `,
      <p className="intro">CSS-in-JS made simple -- just Style It.</p>
    );
  }
}

export default Intro;

And the result as below:

<p class="intro _scoped-1">
  <style type="text/css">
    ._scoped-1.intro {
      font-size: 13px;
    }
    ._scoped-1 .package {
      color: blue;
    }
    ._scoped-1 .package:hover {
      color: aqua;
    }
  </style>

  CSS-in-JS made simple -- just Style It.
</p>

Answer 4

I had a similar issue when onMouseEnter was called but sometimes the corresponding onMouseLeave event wasn't fired, here is a workaround that works well for me (it partially relies on jQuery):

var Hover = React.createClass({
    getInitialState: function() {
        return {
            hover: false
        };
    },
    onMouseEnterHandler: function(e) {
        this.setState({
            hover: true
        });
        console.log('enter');

        $(e.currentTarget).one("mouseleave", function (e) {
            this.onMouseLeaveHandler();
        }.bind(this));

    },
    onMouseLeaveHandler: function() {
        this.setState({
            hover: false
        });
        console.log('leave');
    },
    render: function() {
        var inner = normal;
        if(this.state.hover) {
            inner = hover;
        }

        return (
            <div style={outer}>
                <div style={inner}
                    onMouseEnter={this.onMouseEnterHandler} >
                    {this.props.children}
                </div>
            </div>
        );
    }
});

See on jsfiddle: http://jsfiddle.net/qtbr5cg6/1/

---

Why was it happening (in my case): I am running a jQuery scrolling animation (through $('#item').animate({ scrollTop: 0 })) when clicking on the item. So the cursor doesn't leave the item "naturally", but during a the JavaScript-driven animation ... and in this case the onMouseLeave was not fired properly by React (React 15.3.0, Chrome 51, Desktop)

Answer 5

Have you tried any of these?

onMouseDown onMouseEnter onMouseLeave onMouseMove onMouseOut onMouseOver onMouseUp

SyntheticEvent

it also mentions the following:

React normalizes events so that they have consistent properties across different browsers.

The event handlers below are triggered by an event in the bubbling phase. To register an event handler for the capture phase, append Capture to the event name; for example, instead of using onClick, you would use onClickCapture to handle the click event in the capture phase.

Answer 6

The previous answers are pretty confusing. You don't need a react-state to solve this, nor any special external lib. It can be achieved with pure css/sass:

The style:

.hover {
  position: relative;

  &:hover &__no-hover {
    opacity: 0;
  }

  &:hover &__hover {
    opacity: 1;
  }

  &__hover {
    position: absolute;
    top: 0;
    opacity: 0;
  }

  &__no-hover {
    opacity: 1;
  }
}

The React-Component

A simple Hover Pure-Rendering-Function:

const Hover = ({ onHover, children }) => (
    <div className="hover">
        <div className="hover__no-hover">{children}</div>
        <div className="hover__hover">{onHover}</div>
    </div>
)

Usage

Then use it like this:

    <Hover onHover={<div> Show this on hover </div>}>
        <div> Show on no hover </div>
    </Hover>