心血来潮写一个React的九宫格抽奖组件

 突然想写个react的九宫格抽奖组件,就浅尝一下。写个demo玩玩.

 0.5秒随机点亮奖项,按提供的奖品数组抽奖几率来决定最终中奖;

const items = [
  { id: 1, text: "谢谢惠顾", probability: 0.2 },
  { id: 2, text: "谢谢惠顾", probability: 0.2 },
  { id: 3, text: "谢谢惠顾", probability: 0.2 },
  { id: 4, text: "五等奖", probability: 0.15 },
  { id: 5, text: "四等奖", probability: 0.15 },
  { id: 6, text: "三等奖", probability: 0.09 },
  { id: 7, text: "二等奖", probability: 0.006 },
  { id: 8, text: "一等奖", probability: 0.003 },
  { id: 9, text: "特等奖", probability: 0.001 },
];

import React, { useState, useEffect } from "react";
import "./index.css";

const PrizeGrid = ({ items }) => {
  const [selected, setSelected] = useState(null);
  const [isRunning, setIsRunning] = useState(false);

  useEffect(() => {
    let timerId;
    if (isRunning) {
      timerId = setInterval(() => {
        const randomIndex = Math.floor(Math.random() * 9);
        console.log(randomIndex);
        setSelected(randomIndex);
      }, 500);
    }
    return () => clearTimeout(timerId);
  }, [isRunning, selected]);

  const handleClick = () => {
    if (isRunning) return;
    setIsRunning(true);
    setTimeout(() => {
      setIsRunning(false);
      const randomIndex = selectWinner(items);
      console.log("最后中奖", randomIndex);
      setSelected(randomIndex);
    }, 6000);
  };

  // 按奖品中奖几率抽奖逻辑  
  const selectWinner = (itemsArr) => {
    const probabilities = itemsArr.map((item) => item.probability);
    const sum = probabilities.reduce((acc, val) => acc + val, 0);
    const normalizedProbabilities = probabilities.map((p) => p / sum);

    let cumulativeProbability = 0;
    const cumulativeProbabilities = normalizedProbabilities.map((p) => {
      cumulativeProbability += p;
      return cumulativeProbability;
    });

    const randomNumber = Math.random();
    const selectedIndex = cumulativeProbabilities.findIndex(
      (cp) => randomNumber <= cp
    );

    return selectedIndex + 1;
  };

  return (
    

      {items.map((item, index) => (
        

          {item.text}
        
      ))}
      
        {isRunning ? "Running..." : "Start"}
      
    
  );
};

export default PrizeGrid;

 index.css

.prize-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-gap: 10px;
  margin: 20px;
  width: 300px;
  height: 300px;
}

.prize-grid-item {
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 20px;
  font-weight: bold;
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: #eee;
  color: #333;
  box-shadow: 0px 2px 5px rgba(0, 0, 0, 0.3);
  transition: background-color 0.3s ease-in-out;
}

.prize-grid-item.selected {
  background-color: rgb(223, 113, 10);
}

.prize-grid-button {
  margin: 20px auto;
  display: block;
  padding: 10px;
  background-color: #00f;
  color: #fff;
  font-size: 16px;
  border: none;
  border-radius: 5px;
  cursor: pointer;
}

还有其他的按照几率来随机中奖的工具方法，比如：

1. 概率数组法：将所有奖品的概率存入一个数组中，然后生成一个随机数，根据随机数的值在概率数组中查找对应的奖品。

2. 区间法：将所有奖品的概率转化为区间，然后生成一个0到1之间的随机数，在对应的区间内查找对应的奖品。

3. 权重随机法：将所有奖品按照权重分配一个区间，然后生成一个随机数，根据随机数落在哪个区间来确定中奖的奖品。

这些方法都可以根据具体的需求来选择适合的方法。

1. 概率数组法：

   function getRandomIndexByProbability(probabilityList) {
     const totalProbability = probabilityList.reduce((a, b) => a + b, 0); // 计算总概率
     let random = Math.random() * totalProbability; // 生成随机数
     for (let i = 0; i < probabilityList.length; i++) { // 循环概率数组
       random -= probabilityList[i]; // 减去当前奖品的概率
       if (random < 0) { // 判断是否中奖
         return i; // 返回中奖的奖品索引
       }
     }
   }
   

2. 区间法：

   function getRandomIndexByInterval(intervalList) {
     const random = Math.random(); // 生成随机数
     let probability = 0;
     for (let i = 0; i < intervalList.length; i++) { // 循环区间数组
       if (random >= probability && random < intervalList[i]) { // 判断是否中奖
         return i; // 返回中奖的奖品索引
       }
       probability = intervalList[i]; // 记录上一个区间的概率
     }
   }
   

3. 权重随机法：

   function getRandomIndexByWeight(weights) {
     const totalWeight = weights.reduce((a, b) => a + b, 0); // 计算总权重
     let random = Math.random() * totalWeight; // 生成随机数
     for (let i = 0; i < weights.length; i++) { // 循环权重数组
       random -= weights[i]; // 减去当前奖品的权重
       if (random < 0) { // 判断是否中奖
         return i; // 返回中奖的奖品索引
       }
     }
   }
   

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