Inline CSS styles in React: how to implement a:hover?

Question

I quite like the inline CSS pattern in React and decided to use it.

However, you can\'t use the :hover and similar selectors. So what\'s the best way to

Answer 1

Here's my solution using React Hooks. It combines the spread operator and the ternary operator.

style.js

export default {
  normal:{
    background: 'purple',
    color: '#ffffff'
  },
  hover: {
    background: 'red'
  }
}

Button.js

import React, {useState} from 'react';
import style from './style.js'

function Button(){

  const [hover, setHover] = useState(false);

  return(
    <button
      onMouseEnter={()=>{
        setHover(true);
      }}
      onMouseLeave={()=>{
        setHover(false);
      }}
      style={{
        ...style.normal,
        ...(hover ? style.hover : null)
      }}>

        MyButtonText

    </button>
  )
}

Answer 2

With a using of the hooks:

const useFade = () => {
  const [ fade, setFade ] = useState(false);

  const onMouseEnter = () => {
    setFade(true);
  };

  const onMouseLeave = () => {
    setFade(false);
  };

  const fadeStyle = !fade ? {
    opacity: 1, transition: 'all .2s ease-in-out',
  } : {
    opacity: .5, transition: 'all .2s ease-in-out',
  };

  return { fadeStyle, onMouseEnter, onMouseLeave };
};

const ListItem = ({ style }) => {
  const { fadeStyle, ...fadeProps } = useFade();

  return (
    <Paper
      style={{...fadeStyle, ...style}}
      {...fadeProps}
    >
      {...}
    </Paper>
  );
};

Answer 3

The simple way is using ternary operator

var Link = React.createClass({
  getInitialState: function(){
    return {hover: false}
  },
  toggleHover: function(){
    this.setState({hover: !this.state.hover})
  },
  render: function() {
    var linkStyle;
    if (this.state.hover) {
      linkStyle = {backgroundColor: 'red'}
    } else {
      linkStyle = {backgroundColor: 'blue'}
    }
    return(
      <div>
        <a style={this.state.hover ? {"backgroundColor": 'red'}: {"backgroundColor": 'blue'}} onMouseEnter={this.toggleHover} onMouseLeave={this.toggleHover}>Link</a>
      </div>
    )
  }

Answer 4

I think onMouseEnter and onMouseLeave are the ways to go, but I don't see the need for an additional wrapper component. Here is how I implemented it:

var Link = React.createClass({
  getInitialState: function(){
    return {hover: false}
  },
  toggleHover: function(){
    this.setState({hover: !this.state.hover})
  },
  render: function() {
    var linkStyle;
    if (this.state.hover) {
      linkStyle = {backgroundColor: 'red'}
    } else {
      linkStyle = {backgroundColor: 'blue'}
    }
    return(
      <div>
        <a style={linkStyle} onMouseEnter={this.toggleHover} onMouseLeave={this.toggleHover}>Link</a>
      </div>
    )
}

You can then use the state of hover (true/false) to change the style of the link.

Answer 5

Late to party but come with solution. You can use "&" to defines styles for hover nth Child etc:

day: {
    display: "flex",
    flex: "1",
    justifyContent: "center",
    alignItems: "center",
    width: "50px",
    height: "50px",
    transition: "all 0.2s",
    borderLeft: "solid 1px #cccccc",

    "&:hover": {
      background: "#efefef"
    },
    "&:last-child": {
      borderRight: "solid 1px #cccccc"
    }
},

Answer 6

Made Style It -- in part -- because of this reason (others being disagreements with implementation of other libs / syntax and inline stylings lack of support for prefixing property values). Believe we should be able to simply write CSS in JavaScript and have fully self contained components HTML-CSS-JS. With ES5 / ES6 template strings we now can and it can be pretty too! :)

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;