19

I have a react single page app, with multiple components. For the 5th component(visible only when scrolled down) I have a counter . Now I am using react-countup library to achieve the counter function. However , the counter starts soon as the page is loaded . Is it possible for countup to begin once we scroll down to the component. Animation happens only once(which is good)after the page is loaded, but I would like the counter not to begin soon after the page is loaded, but when user scrolls down to the component the first time. My code looks like this:

    render() {
         return (
         <div className={style.componentName}>
         <h2>Heading</h2>
         <div className={style.col}>
         <div>My counter</div>
         <CountUp className={style.countup} decimals={1} start={0} end={25} suffix=" %" duration={3} />
        </div>
        </div>)}

Updated code:

    import CountUp, { startAnimation } from 'react-countup';
    import VisibilitySensor from 'react-visibility-sensor';

    class className extends Component {

        state = {
            scrollStatus: true
        };


        onVisibilityChange = isVisible => {
            if (isVisible) {
                if (this.state.scrollStatus) {
                    startAnimation(this.myCountUp);
                    this.setState({ scrollStatus: false });
                }
            }
        }
    render() {
             return (
            <div className={style.componentName}>
             <h2>Heading</h2>
             <VisibilitySensor onChange={this.onVisibilityChange} offset = {{ top: 
              10}} delayedCall>
             <CountUp className={style.countup} decimals={1} start={0} end={25} 
             suffix=" %" duration={3} ref={countUp => { this.myCountUp= countUp;}}/>
             </VisibilitySensor>
            </div>)}
}
user659730
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10 Answers10

35

The API may have changed since last year. I manage to make this work with this code now :

import React from "react";
import CountUp from "react-countup";
import VisibilitySensor from 'react-visibility-sensor';

const MyComponent = () => (
  <>
    <CountUp end={100} redraw={true}>
        {({ countUpRef, start }) => (
            <VisibilitySensor onChange={start} delayedCall>
                <span ref={countUpRef} />
            </VisibilitySensor>
        )}
    </CountUp>
  </>
);

export default App;

I use this component inside a tab, so the redraw={true} prop is only here to redraw the animation on tabChange.

Charming Robot
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Thibault
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9

Per React CountUp's README, you can use the startAnimation hook to manually kick off the animation. Combine this with something like react-visibility-sensor, and you can wait to kick off the animation until it is visible in the user's browser.

import React, {Component} from 'react';
import CountUp, {startAnimation} from 'react-countup';
import './App.css';
import VisibilitySensor from 'react-visibility-sensor';

const style = {
  componentName: {},
  col: {},
  countup: {},
};

class App extends Component {
  constructor(props) {
    super(props);
    this.onVisibilityChange = this.onVisibilityChange.bind(this); // Bind for appropriate 'this' context
  }

  onVisibilityChange(isVisible) {
    if (isVisible) {
      startAnimation(this.myCountUp);
    }
  }

  render() {
    return (
      <div className={style.componentName}>
        <h2>Heading</h2>
        <div className={style.col}>
          <div>My counter</div>
          <VisibilitySensor
            onChange={this.onVisibilityChange}
            delayedCall // Prevents react apps triggering elements as visible before styles are loaded
          >
            <CountUp className={style.countup} decimals={1} start={0} end={25} suffix=" %" duration={3}
                     ref={countUp => { this.myCountUp = countUp; }} // From react-countup README 
            />
          </VisibilitySensor>
        </div>
      </div>
    );
  }
}

export default App;

As is, it will startAnimation every time you scroll to the countup. If you want to only do that once, just add a piece of state that gets set after the first render (and then prevent it from doing startAnimation again based on that altered state).

Less elegant (not recommended) ways to accomplish the same effect might include:

  • Use the built-in animation triggers (i.e. changing the props duration, end, start) by setting them equal to some state that changes when the user scrolls down
  • Leveraging the onStart prop, called before the animation starts, to delay starting the animation until the user scrolls down

EDIT: Update to address your second question

Unfortunately, it looks like the react-countup library doesn't expose a way to prevent startAnimation on startup.

But we can hack together a fairly elegant fix by manipulating the end prop using state instead:

import React, {Component} from 'react';
import CountUp, {startAnimation} from 'react-countup';
import './App.css';
import VisibilitySensor from 'react-visibility-sensor';

const style = {
  componentName: {},
  col: {},
  countup: {},
};

class App extends Component {
  state = {
    didViewCountUp: false
  };


  onVisibilityChange = isVisible => {
    if (isVisible) {
      this.setState({didViewCountUp: true});
    }
  }

  render() {
    return (
      <div className={style.componentName}>
        <h2 style={{fontSize: '40em'}}>Heading</h2>
        <VisibilitySensor onChange={this.onVisibilityChange} offset={{
          top:
            10
        }} delayedCall>
          <CountUp className={style.countup} decimals={1} start={0} end={this.state.didViewCountUp ? 25 : 0}
                   suffix=" %" duration={3} />
        </VisibilitySensor>
      </div>)
  }
}

export default App;
Tadas Antanavicius
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  • used state to set a value after first render. It works perfectly! Thank you very much. :) But one small bug,the counter at the beginning is at end count=25 and animation starts on scroll to the component. i.e there's a small amount of time before animation of 0-25 start. – user659730 Jul 03 '18 at 13:39
  • Could you edit your question with the updated code? Will help to try it out and maybe can suggest a fix in the context of what you have – Tadas Antanavicius Jul 03 '18 at 15:13
  • I updated the code. it is exactly as the code that ur answer. Using state to do the "startAnimation" just once. – user659730 Jul 07 '18 at 13:41
4

Here's my implementation. It just runs once and also doesn't re-render every time the component enters viewport to check visibility.

Dependencies:
1. react-countup v.4.3.2
2. react-visibility-sensor v.5.1.1

import React, { useState } from "react";
import CountUp from "react-countup";
import VisibilitySensor from "react-visibility-sensor";

const Ticker = ({ className, ...rest }) => {
  const [viewPortEntered, setViewPortEntered] = useState(false);

  return (
    <CountUp {...rest} start={viewPortEntered ? null : 0}>
      {({ countUpRef }) => {
        return (
          <VisibilitySensor
            active={!viewPortEntered}
            onChange={isVisible => {
              if (isVisible) {
                setViewPortEntered(true);
              }
            }}
            delayedCall
          >
            <h4 className={className} ref={countUpRef} />
          </VisibilitySensor>
        );
      }}
    </CountUp>
  );
};

export default Ticker;

Here's how to use it:

<Ticker className="count" end={21} suffix="M+" />
Sushmit Sagar
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3

Here is my solution using class based component Note: import two Libraries first run this code react-visibility-sensor react-countup

import React from "react";
import CountUp from "react-countup";
import VisibilitySensor from 'react-visibility-sensor';

class CountDown extends React.Component {
    render() {
        return (
            
                <React.Fragment>
                    <CountUp start={0} end={100} prefix="+" duration="2">

                        {({ countUpRef, start }) => (
                            <VisibilitySensor onChange={start} delayedCall>
                                <span ref={countUpRef} />
                            </VisibilitySensor>
                        )}

                    </CountUp>
                </React.Fragment>
           

        )
    }
}

export default CountDown;
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
2

Simply add below prop

enableScrollSpy: true

<CountUp enableScrollSpy={true} end={75}/>
1

The docs for that library have a way to manually start the counter. I would use that approach to start the counter once a user has scrolled to the required distance.

import React, { Component } from 'react';
import CountUp, { startAnimation } from 'react-countup';

const MyComponent = () => (
  <div>
    <CountUp className="CountUp" start={0} end={100} duration={3} ref={(countUp) => {
      this.myCountUp = countUp;
    }} />
    <button className="Button" onClick={(event) => {
      startAnimation(this.myCountUp);
    }}>Count me up!</button>
  </div>
);

export default App;

Link to Github. Read the README at the very bottom.

Matthew Mallimo
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1

you can have look at my functional component to achieve this

import React from "react";
    import { Box } from "@material-ui/core";
    import CountUp from "react-countup";
    import VisibilitySensor from "react-visibility-sensor";

    export default function Counter() {
      const [focus, setFocus] = React.useState(false);
      return (
        <Box component="div">
          <CountUp start={focus ? 0 : null} end={100} duration={5} redraw={true}>
            {({ countUpRef }) => (
              <div>
                <span ref={countUpRef} />
                <VisibilitySensor
                  onChange={isVisible => {
                    if (isVisible) {
                      setFocus(true);
                    } 
                  }}
                >
                  <a>+</a>
                </VisibilitySensor>
              </div>
            )}
          </CountUp>
        </Box>
      );
    }
Gagan V
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0

react-visibility-sensor doesn't seem to be maintained at the moment and produces warnings related to findDOMNode which is deprecated.

I've used react-waypoint in my functional component which makes the animation only trigger once when the user has the child of the waypoint component in view.

    // Ticker.tsx

import React, { useState } from "react";
import CountUp from "react-countup";
import { Waypoint } from "react-waypoint";

type TickerProps = {
  end: number;
  suffix: string;
}

const Ticker: React.FC<TickerProps> = ({ end, suffix }) => {
  const [viewPortEntered, setViewPortEntered] = useState(false);

  const onVWEnter = () => {
    setViewPortEntered(true);
  }

    return (
      <Waypoint onEnter={onVWEnter} >
        <div>
          {viewPortEntered && <CountUp end={end} suffix={suffix} start={0} /> }
        </div>
      </Waypoint>
    );
};

export default Ticker;
uana13
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0
<CountUp
        className={styles.number}
        start={0}
        end={number}
        enableScrollSpy={true}
        scrollSpyDelay={0}
        suffix={index !== -1 ? "+" : ""}
/>

try this scroll spy should do the work

0

Here's an alternative solution using react-in-viewport package. Idea is to define this element and use <CountUpInViewport> instead of <CountUp>.

This example fires on the first entry. One could do variations on this to refire every time it enters/leaves the viewport.


import React from 'react';
import { useRef } from 'react';
import CountUp from 'react-countup';
import { useInViewport } from 'react-in-viewport';

let CountUpInViewport = props => {
  const ref = useRef();
  const { enterCount } = useInViewport(ref);
  return (
    <div ref={ref}>
      {
        enterCount > 0 ?
        <CountUp key='in' {...props}></CountUp> :
        <CountUp key='out' {...props}></CountUp>  // ensures drawn when not visible
      }
    </div>
  );
}
GratefulGuest
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