如何用 160 行代码，实现动态炫酷的可视化图表？

准备通用工具函数

getRandomColor：随机颜色

const getRandomColor = () => {
const letters = '0123456789ABCDEF';
let color = '#';
for (let i = 0; i < 6; i++) {
color += letters[Math.floor(Math.random() * 16)]
}
return color;
};

translateY：填充Y轴偏移量

const translateY = (value) => {
return translateY(${value}px);
}

使用useState Hook声明状态变量

我们开始编写组件DynamicBarChart

const DynamicBarChart = (props) => {
const [dataQueue, setDataQueue] = useState([]);
const [activeItemIdx, setActiveItemIdx] = useState(0);
const [highestValue, setHighestValue] = useState(0);
const [currentValues, setCurrentValues] = useState({});
const [firstRun, setFirstRun] = useState(false);
// 其它代码...
}

useState的简单理解：
const [属性, 操作属性的方法] = useState(默认值);
变量解析
dataQueue：当前操作的原始数据数组
activeItemIdx: 第几“帧”
highestValue: “榜首”的数据值
currentValues: 经过处理后用于渲染的数据数组
firstRun: 第一次动态渲染时间
内部操作方法和对应useEffect
请配合注释使用：

// 动态跑起来～
function start () {
if (activeItemIdx > 1) {
return;
}
nextStep(true);
}
// 对下一帧数据进行处理
function setNextValues () {
// 没有帧数时（即已结束），停止渲染
if (!dataQueue[activeItemIdx]) {
iterationTimeoutHolder = null;
return;
}
// 每一帧的数据数组
const roundData = dataQueue[activeItemIdx].values;
const nextValues = {};
let highestValue = 0;
// 处理数据，用作最后渲染（各种样式，颜色）
roundData.map((c) => {
nextValues[c.id] = {
...c,
color: c.color || (currentValues[c.id] || {}).color || getRandomColor()
};

if (Math.abs(c.value) > highestValue) {
  highestValue = Math.abs(c.value);
}

return c;

});

// 属性的操作，触发useEffect
setCurrentValues(nextValues);
setHighestValue(highestValue);
setActiveItemIdx(activeItemIdx + 1);
}
// 触发下一步，循环
function nextStep (firstRun = false) {
setFirstRun(firstRun);
setNextValues();
}
对应useEffect：
// 取原始数据
useEffect(() => {
setDataQueue(props.data);
}, []);
// 触发动态
useEffect(() => {
start();
}, [dataQueue]);
// 设触发动态间隔
useEffect(() => {
iterationTimeoutHolder = window.setTimeout(nextStep, 1000);
return () => {
if (iterationTimeoutHolder) {
window.clearTimeout(iterationTimeoutHolder);
}
};
}, [activeItemIdx]);
useEffect示例：
useEffect(() => {
document.title = You clicked ${count} times;
}, [count]); // 仅在 count 更改时更新
为什么要在 effect 中返回一个函数？
这是 effect 可选的清除机制。每个 effect 都可以返回一个清除函数。如此可以将添加和移除订阅的逻辑放在一起。
整理用于渲染页面的数据
const keys = Object.keys(currentValues);
const { barGapSize, barHeight, showTitle } = props;
const maxValue = highestValue / 0.85;
const sortedCurrentValues = keys.sort((a, b) => currentValues[b].value - currentValues[a].value);
const currentItem = dataQueue[activeItemIdx - 1] || {};
keys: 每组数据的索引
maxValue: 图表最大宽度

sortedCurrentValues: 对每组数据进行排序，该项影响动态渲染。

currentItem: 每组的原始数据

开始渲染页面
大致的逻辑就是：

根据不同Props,循环排列后的数据：sortedCurrentValues

计算宽度，返回每项的label、bar、value

根据计算好的高度，触发transform。

<div className="live-chart">
{
<React.Fragment>
{
showTitle &&
<h1>{currentItem.name}</h1>
}
<section className="chart">
<div className="chart-bars" style={{ height: (barHeight + barGapSize) keys.length }}>
{
sortedCurrentValues.map((key, idx) => {
const currentValueData = currentValues[key];
const value = currentValueData.value
let width = Math.abs((value / maxValue 100));
let widthStr;
if (isNaN(width) || !width) {
widthStr = '1px';
} else {
widthStr = ${width}%;
}

      return (
        <div className={`bar-wrapper`} style={{ transform: translateY((barHeight + barGapSize) * idx), transitionDuration: 200 / 1000 }} key={`bar_${key}`}>
          <label>
            {
              !currentValueData.label
                ? key
                : currentValueData.label
            }
          </label>
          <div className="bar" style={{ height: barHeight, width: widthStr, background: typeof currentValueData.color === 'string' ? currentValueData.color : `linear-gradient(to right, ${currentValueData.color.join(',')})` }} />
          <span className="value" style={{ color: typeof currentValueData.color === 'string' ? currentValueData.color : currentValueData.color[0] }}>{currentValueData.value}</span>
        </div>
      );
    })
  }
</div>

</section>
</React.Fragment>
}
</div>

定义常规propTypes和defaultProps

DynamicBarChart.propTypes = {
showTitle: PropTypes.bool,
iterationTimeout: PropTypes.number,
data: PropTypes.array,
startRunningTimeout: PropTypes.number,
barHeight: PropTypes.number,
barGapSize: PropTypes.number,
baseline: PropTypes.number,
};

DynamicBarChart.defaultProps = {
showTitle: true,
iterationTimeout: 200,
data: [],
startRunningTimeout: 0,
barHeight: 50,
barGapSize: 20,
baseline: null,
};

export {
DynamicBarChart
};

如何使用

import React, { Component } from "react";

import { DynamicBarChart } from "./DynamicBarChart";

import helpers from "./helpers";
import mocks from "./mocks";

import "react-dynamic-charts/dist/index.css";

export default class App extends Component {
render() {
return (
<DynamicBarChart
barGapSize={10}
data={helpers.generateData(100, mocks.defaultChart, {
prefix: "Iteration"
})}
iterationTimeout={100}
showTitle={true}
startRunningTimeout={2500}
/>
)
}
}

批量生成Mock数据

helpers.js:
function getRandomNumber(min, max) {
return Math.floor(Math.random() * (max - min + 1) + min);
};

export default {
getRandomNumber,
generateData
}

mocks.js:

import helpers from './helpers';
const defaultChart = [
{
id: 1,
label: 'Google',
value: helpers.getRandomNumber(0, 50)
},
{
id: 2,
label: 'Facebook',
value: helpers.getRandomNumber(0, 50)
},
{
id: 3,
label: 'Outbrain',
value: helpers.getRandomNumber(0, 50)
},
{
id: 4,
label: 'Apple',
value: helpers.getRandomNumber(0, 50)
},
{
id: 5,
label: 'Amazon',
value: helpers.getRandomNumber(0, 50)
},
];
export default {
defaultChart,
}
一个乞丐版的动态排行榜可视化就做好喇。
完整代码
import React, { useState, useEffect } from 'react';
import PropTypes from 'prop-types';
import './styles.scss';

const getRandomColor = () => {
const letters = '0123456789ABCDEF';
let color = '#';
for (let i = 0; i < 6; i++) {
color += letters[Math.floor(Math.random() * 16)]
}
return color;
};

const translateY = (value) => {
return translateY(${value}px);
}

function start () {
if (activeItemIdx > 1) {
return;
}
nextStep(true);
}

function setNextValues () {
if (!dataQueue[activeItemIdx]) {
iterationTimeoutHolder = null;
return;
}

const roundData = dataQueue[activeItemIdx].values;
const nextValues = {};
let highestValue = 0;
roundData.map((c) => {
  nextValues[c.id] = {
    ...c,
    color: c.color || (currentValues[c.id] || {}).color || getRandomColor()
  };

  if (Math.abs(c.value) > highestValue) {
    highestValue = Math.abs(c.value);
  }

  return c;
});
console.table(highestValue);
    www.kaifx.cn

setCurrentValues(nextValues);
setHighestValue(highestValue);
setActiveItemIdx(activeItemIdx + 1);

}

function nextStep (firstRun = false) {
setFirstRun(firstRun);
setNextValues();
}

useEffect(() => {
setDataQueue(props.data);
}, []);

useEffect(() => {
start();
}, [dataQueue]);

useEffect(() => {
iterationTimeoutHolder = window.setTimeout(nextStep, 1000);
return () => {
if (iterationTimeoutHolder) {
window.clearTimeout(iterationTimeoutHolder);
}
};
}, [activeItemIdx]);

const keys = Object.keys(currentValues);
const { barGapSize, barHeight, showTitle, data } = props;
console.table('data', data);
const maxValue = highestValue / 0.85;
const sortedCurrentValues = keys.sort((a, b) => currentValues[b].value - currentValues[a].value);
const currentItem = dataQueue[activeItemIdx - 1] || {};

return (
<div className="live-chart">
{
<React.Fragment>
{
showTitle &&
<h1>{currentItem.name}</h1>
}
<section className="chart">
<div className="chart-bars" style={{ height: (barHeight + barGapSize) keys.length }}>
{
sortedCurrentValues.map((key, idx) => {
const currentValueData = currentValues[key];
const value = currentValueData.value
let width = Math.abs((value / maxValue 100));
let widthStr;
if (isNaN(width) || !width) {
widthStr = '1px';
} else {
widthStr = ${width}%;
}

              return (
                <div className={`bar-wrapper`} style={{ transform: translateY((barHeight + barGapSize) * idx), transitionDuration: 200 / 1000 }} key={`bar_${key}`}>
                  <label>
                    {
                      !currentValueData.label
                        ? key
                        : currentValueData.label
                    }
                  </label>
                  <div className="bar" style={{ height: barHeight, width: widthStr, background: typeof currentValueData.color === 'string' ? currentValueData.color : `linear-gradient(to right, ${currentValueData.color.join(',')})` }} />
                  <span className="value" style={{ color: typeof currentValueData.color === 'string' ? currentValueData.color : currentValueData.color[0] }}>{currentValueData.value}</span>
                </div>
              );
            })
          }
        </div>
      </section>
    </React.Fragment>
  }
</div>

);
};

DynamicBarChart.defaultProps = {
showTitle: true,
iterationTimeout: 200,
data: [],
startRunningTimeout: 0,
barHeight: 50,
barGapSize: 20,
baseline: null,
};

export {
DynamicBarChart
};

styles.scss

.live-chart {
width: 100%;
padding: 20px;
box-sizing: border-box;
position: relative;
text-align: center;
h1 {
font-weight: 700;
font-size: 60px;
text-transform: uppercase;
text-align: center;
padding: 20px 10px;
margin: 0;
}

.chart {
position: relative;
margin: 20px auto;
}

.chart-bars {
position: relative;
width: 100%;
}

.bar-wrapper {
display: flex;
flex-wrap: wrap;
align-items: center;
position: absolute;
top: 0;
left: 0;
transform: translateY(0);
transition: transform 0.5s linear;
padding-left: 200px;
box-sizing: border-box;
width: 100%;
justify-content: flex-start;

label {
  position: absolute;
  height: 100%;
  width: 200px;
  left: 0;
  padding: 0 10px;
  box-sizing: border-box;
  text-align: right;
  top: 50%;
  transform: translateY(-50%);
  font-size: 16px;
  font-weight: 700;
  display: flex;
  justify-content: flex-end;
  align-items: center;
}

.value {
  font-size: 16px;
  font-weight: 700;
  margin-left: 10px;
}

.bar {
  width: 0%;
  transition: width 0.5s linear;
}

}
}
结语
一直对实现动态排行榜可视化感兴趣，无奈多数都是基于D3或echarts实现。
而这个库，不仅脱离图形库，还使用了React 16的新特性。也让我彻底理解了React Hook的妙用。

如何用 160 行代码，实现动态炫酷的可视化图表？

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