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Create simple animated bar chart in React

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Created by:

Paris-Bateman

504

Did you know you don't need much to build an animated bar chart?
In this article, I will try to explain how to get such an effect with React. 📊

Final effect of the post:

The main idea is to create individual bars that are described from 0 to 100%. The bars are arranged sequentially next to each other in a chart, using an example data set
based on the cosine function.

Each change of the dataset describing the chart causes a smooth re-rendering (this happens due to a simple style called transition).

The whole effect is achieved with a few lines, most of the effect is actually styles. 🎨

Practical example:

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// import React from 'react';
// import ReactDOM from 'react-dom';
​
// ---------------------------------
​
const containerStyle = {
    padding: '0 1px',
    background: '#ffffff',
    flex: '1'
};
​
const spaceStyle = {
    background: '#ffffff',
    transition: '0.3s'
};
​
const barStyle = {
    background: '#00cc00',
    transition: '0.3s'
};
​
const Bar = ({value}) => {
    return (
      <div style={containerStyle}>
        <div style={{...spaceStyle, height: `${100 - value}%`}} />
        <div style={{...barStyle, height: `${value}%`}} />
      </div>
    );
};
​
const chartStyle = {
    width: '400px',
    height: '300px',
    display: 'flex',
    overflow: 'hidden'
};
​
const Chart = ({data}) => {
    return (
      <div style={chartStyle}>
        {data.map((value, index) => <Bar key={index} value={value} />)}
      </div>
    );
};
​
// ---------------------------------
​
const calculateData = (xOffset) => {
    const data = [ ];
    for (var x = 0; x < 3.1415; x += 0.1) {
        const y = Math.cos(x + xOffset) + 1;
        data.push(50 * y);
    }
    return data;
};
​
const App = () => {
    const [data, setData] = React.useState(() => calculateData(0));
    const xOffsets = [0, 0.7853, 1.5707, 2.3559, 3.1415];
    return (
      <div>
        <Chart data={data} />
        <br />
        <div>
          <span>xOffset: </span>
          {xOffsets.map(xOffset => {
              const handleClick = () => setData(calculateData(xOffset));
              return (
                <button key={xOffset} onClick={handleClick}>{xOffset}</button>
              );
          })}
        </div>
      </div>
    );
};
​
const root = document.querySelector('#root');
ReactDOM.render(<App />, root);