Get viewport/window height in ReactJS

Question

Using Hooks (React 16.8.0+)

Create a useWindowDimensions hook.

import { useState, useEffect } from 'react';

function getWindowDimensions() {
  const { innerWidth: width, innerHeight: height } = window;
  return {
    width,
    height
  };
}

export default function useWindowDimensions() {
  const [windowDimensions, setWindowDimensions] = useState(getWindowDimensions());

  useEffect(() => {
    function handleResize() {
      setWindowDimensions(getWindowDimensions());
    }

    window.addEventListener('resize', handleResize);
    return () => window.removeEventListener('resize', handleResize);
  }, []);

  return windowDimensions;
}

And after that you'll be able to use it in your components like this

const Component = () => {
  const { height, width } = useWindowDimensions();

  return (
    <div>
      width: {width} ~ height: {height}
    </div>
  );
}

Working example

Original answer

It's the same in React, you can use window.innerHeight to get the current viewport's height.

As you can see here

This answer is similar to Jabran Saeed's, except it handles window resizing as well. I got it from here.

constructor(props) {
  super(props);
  this.state = { width: 0, height: 0 };
  this.updateWindowDimensions = this.updateWindowDimensions.bind(this);
}

componentDidMount() {
  this.updateWindowDimensions();
  window.addEventListener('resize', this.updateWindowDimensions);
}

componentWillUnmount() {
  window.removeEventListener('resize', this.updateWindowDimensions);
}

updateWindowDimensions() {
  this.setState({ width: window.innerWidth, height: window.innerHeight });
}

class AppComponent extends React.Component {

  constructor(props) {
    super(props);
    this.state = {height: props.height};
  }

  componentWillMount(){
    this.setState({height: window.innerHeight + 'px'});
  }

  render() {
    // render your component...
  }
}

Set the props

AppComponent.propTypes = {
 height:React.PropTypes.string
};

AppComponent.defaultProps = {
 height:'500px'
};

viewport height is now available as {this.state.height} in rendering template

I've just edited QoP's current answer to support SSR and use it with Next.js (React 16.8.0+):

/hooks/useWindowDimensions.js:

import { useState, useEffect } from 'react';

export default function useWindowDimensions() {

  const hasWindow = typeof window !== 'undefined';

  function getWindowDimensions() {
    const width = hasWindow ? window.innerWidth : null;
    const height = hasWindow ? window.innerHeight : null;
    return {
      width,
      height,
    };
  }

  const [windowDimensions, setWindowDimensions] = useState(getWindowDimensions());

  useEffect(() => {
    if (hasWindow) {
      function handleResize() {
        setWindowDimensions(getWindowDimensions());
      }

      window.addEventListener('resize', handleResize);
      return () => window.removeEventListener('resize', handleResize);
    }
  }, [hasWindow]);

  return windowDimensions;
}

/yourComponent.js:

import useWindowDimensions from './hooks/useWindowDimensions';

const Component = () => {
  const { height, width } = useWindowDimensions();
  /* you can also use default values or alias to use only one prop: */
  // const { height: windowHeight = 480 } useWindowDimensions();

  return (
    <div>
      width: {width} ~ height: {height}
    </div>
  );
}

I found a simple combo of QoP and speckledcarp's answer using React Hooks and resizing features, with slightly less lines of code:

const [width, setWidth]   = useState(window.innerWidth);
const [height, setHeight] = useState(window.innerHeight);
const updateDimensions = () => {
    setWidth(window.innerWidth);
    setHeight(window.innerHeight);
}
useEffect(() => {
    window.addEventListener("resize", updateDimensions);
    return () => window.removeEventListener("resize", updateDimensions);
}, []);

Oh yeah make sure that the resize event is in double quotes, not single. That one got me for a bit ;)

@speckledcarp 's answer is great, but can be tedious if you need this logic in multiple components. You can refactor it as an HOC (higher order component) to make this logic easier to reuse.

withWindowDimensions.jsx

import React, { Component } from "react";

export default function withWindowDimensions(WrappedComponent) {
    return class extends Component {
        state = { width: 0, height: 0 };

        componentDidMount() {
            this.updateWindowDimensions();
            window.addEventListener("resize", this.updateWindowDimensions);
        }

        componentWillUnmount() {
            window.removeEventListener("resize", this.updateWindowDimensions);
        }

        updateWindowDimensions = () => {
            this.setState({ width: window.innerWidth, height: window.innerHeight });
        };

        render() {
            return (
                <WrappedComponent
                    {...this.props}
                    windowWidth={this.state.width}
                    windowHeight={this.state.height}
                    isMobileSized={this.state.width < 700}
                />
            );
        }
    };
}

Then in your main component:

import withWindowDimensions from './withWindowDimensions.jsx';

class MyComponent extends Component {
  render(){
    if(this.props.isMobileSized) return <p>It's short</p>;
    else return <p>It's not short</p>;
}

export default withWindowDimensions(MyComponent);

You can also "stack" HOCs if you have another you need to use, e.g. withRouter(withWindowDimensions(MyComponent))

Edit: I would go with a React hook nowadays (example above here), as they solve some of the advanced issues with HOCs and classes