在 JSX 中悬停时更改图像

Question

How do I change an image on hover in JSX

I'm trying something like this:

<img src={require('../../../common/assets/network-inactive.png')}
onMouseOver={this.src = require('../../../common/assets/network.png')}
onMouseOut={this.src = require('../../../common/assets/network-inactive.png')} />

Answer 1

I will assume you are writing this code in a React component. Such as:

class Welcome extends React.Component {
  render() {
    return (
       <img src={require('../../../common/assets/network-inactive.png')}
       onMouseOver={this.src = require('../../../common/assets/network.png')}
       onMouseOut={this.src = require('../../../common/assets/network-inactive.png')} 
       />
    );
  }
}

Targeting this.src will not work in this case as you are essentially looking for something named src in your class. For instance this.src could find something like this:

src = () => (alert("a source"))

But that is not what you want to do. You want to target the image itself.

Therfore you need to enter the <img /> context. You can do that easily like this:

 <img
    onMouseOver={e => console.log(e)}
  />

From there you can target the currentTarget property, among others. This will enter the context of your element. So now you can do something like this:

  <img
    src="img1"
    onMouseOver={e => (e.currentTarget.src = "img2")}
  />

The same can be done for onMouseOut .

You can use this same method on your other elements, as you will certainly need to do this again. But be careful as this is a not the only solution. On bigger projects you may want to consider using a store ( Redux ), and passing props rather than mutating elements.

Answer 2

Best is to manage this in the state:

class App extends Component {
  state = {
    img: "https://i.vimeocdn.com/portrait/58832_300x300"
  }

  render() {
    return (
      <div style={styles}>
        <img
          src={this.state.img}
          onMouseEnter={() => {
            this.setState({
              img: "http://www.toptipsclub.com/Images/page-img/keep-calm-and-prepare-for-a-test.png"
            })
          }}

          onMouseOut={() => {
            this.setState({
              img: "https://i.vimeocdn.com/portrait/58832_300x300"
            })
          }}
        />
      </div>
    )
  }
};

https://codesandbox.io/s/5437qm907l

Answer 3

Here's a non-class approach using a functional component and typescript:

interface IconProps {
  src?: string;
  srcOnHover?: string;
  alt?: string;
}

const Icon: React.FC<IconProps> = ({ src, srcOnHover, alt }) => (
  <img
    src={src}
    alt={alt}
    onMouseOver={(e): void => {
      srcOnHover && (e.currentTarget.src = srcOnHover);
    }}
    onMouseOut={(e): void => {
      srcOnHover && (e.currentTarget.src = src || '');
    }}
  />
);

It can be used like that:

<Icon src="path/to/image.png" srcOnHover="path/to/hover-image.png" alt="Description" />

Answer 4

simple way to do this:

class Home extends React.Component { state = { icon: ICON_ONE }

render(){ return( <img src={this.state.icon} onMouseOver={()=>this.setState({icon:ICON_TWO})}
onMouseOut={() => this.setState({ icon: ICON_ONE })} /> ) }

Answer 5

Another non-class approach:

import arrow from "../images/arrow.svg";
import arrowHover from "../images/arrowHover.svg";

function Arrow() {
  const [over, setOver] = useState(false);
  return (
    <div
      onMouseOver={() => setOver(true)}
      onMouseOut={() => setOver(false)}
    >
         <img
          src={over ? arrowHover : arrow}
          alt="arrow"
          width="50"
          height="50"
        />
    </div>   
  )
}