<Scrollama onStepEnter={callback} offset={0.5}>
  <Step data={1}>
    <div>...</div>
  </Step>
  <Step data={2}>
    <div>...</div>
  </Step>
</Scrollama>

import React, { useState } from 'react';
import { Scrollama, Step } from 'react-scrollama';

const ScrollamaDemo = () => {
  const [currentStepIndex, setCurrentStepIndex] = useState(null);

  // This callback fires when a Step hits the offset threshold. It receives the
  // data prop of the step, which in this demo stores the index of the step.
  const onStepEnter = ({ data }) => {
    setCurrentStepIndex(data);
  };

  return (
    <div style={{ margin: '50vh 0', border: '2px dashed skyblue' }}>
      <div style={{ position: 'sticky', top: 0, border: '1px solid orchid' }}>
        I'm sticky. The current triggered step index is: {currentStepIndex}
      </div>
      <Scrollama offset={0.5} onStepEnter={onStepEnter} debug>
        {[1, 2, 3, 4].map((_, stepIndex) => (
          <Step data={stepIndex} key={stepIndex}>
            <div
              style={{
                margin: '50vh 0',
                border: '1px solid gray',
                opacity: currentStepIndex === stepIndex ? 1 : 0.2,
              }}
            >
              I'm a Scrollama Step of index {stepIndex}
            </div>
          </Step>
        ))}
      </Scrollama>
    </div>
  );
};

export default ScrollamaDemo;

{
  element, // The DOM node of the step that was triggered
  data, // The data supplied to the step
  direction, // 'up' or 'down'
  entry, // the original `IntersectionObserver` entry
}

{
  element, // The DOM node of the step that was triggered
  data, // The data supplied to the step
  progress, // The percent of completion of the step (0 to 1)
  direction, // 'up' or 'down'
  entry, // the original `IntersectionObserver` entry
}