抽奖程序demo以及随机数设置

转自 https://codepen.io/mirari/pen/XLgBQP

<template>
  <div>
    <span>Prize number: {{ prizeNumber }}</span>
    <button type="button" @click="!rolling && prizeNumber < 8 && (prizeNumber++)"
            :disabled="rolling || prizeNumber === 8">Add
    </button>
    <button type="button" @click="!rolling && prizeNumber > 2 && (prizeNumber--)"
            :disabled="rolling || prizeNumber === 2">Remove
    </button>
    <div class="wheel-wrapper">
      <div
        class="wheel-pointer"
        @click="onClickRotate"
      >
        Start
      </div>
      <div
        class="wheel-bg"
        :class="{freeze: freeze}"
        :style="`transform: rotate(${wheelDeg}deg)`"
      >
        <div class="prize-list">
          <div
            class="prize-item-wrapper"
            v-for="(item,index) in prizeList"
            :key="index"
          >
            <div
              class="prize-item"
              :style="`transform: rotate(${(360/ prizeList.length) * index}deg)`"
            >
              <div class="prize-name">
                {{ item.name }}
              </div>
              <div class="prize-icon">
                <img :src="item.icon">
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>
</template>

<script>
  export default {
    name: 'cj',
    data() {
      return {
        freeze: false,
        rolling: false,
        wheelDeg: 0,
        prizeNumber: 8,
        prizeListOrigin: [
          {
            icon: 'https://picsum.photos/40?random=1',
            name: '$10000'
          },
          {
            icon: 'https://picsum.photos/40?random=6',
            name: 'Thank you!'
          },
          {
            icon: 'https://picsum.photos/40?random=2',
            name: '$500'
          },
          {
            icon: 'https://picsum.photos/40?random=3',
            name: '$100'
          },
          {
            icon: 'https://picsum.photos/40?random=6',
            name: 'Thank you!'
          },
          {
            icon: 'https://picsum.photos/40?random=4',
            name: '$50'
          },
          {
            icon: 'https://picsum.photos/40?random=5',
            name: '$10'
          },
          {
            icon: 'https://picsum.photos/40?random=6',
            name: 'Thank you!'
          }
        ]
      }
    },
    computed: {
      prizeList() {
        return this.prizeListOrigin.slice(0, this.prizeNumber);
      }
    },
    methods: {
      onClickRotate() {
        if (this.rolling) {
          return;
        }
        const result = Math.floor(Math.random() * this.prizeList.length);
        this.roll(result);
      },
      roll(result) {
        this.rolling = true;
        const {wheelDeg, prizeList} = this;
        this.wheelDeg =
          wheelDeg -
          wheelDeg % 360 +
          6 * 360 +
          (360 - 360 / prizeList.length * result);
        setTimeout(() => {
          this.rolling = false;
          alert('Result：' + prizeList[result].name);
        }, 4500);
      }
    },
    watch: {
      prizeNumber() {
        this.freeze = true;
        this.wheelDeg = 0;

        setTimeout(() => {
          this.freeze = false;
        }, 0);
      }
    }
  }
</script>

<style lang="stylus" scoped>
  .wheel-wrapper {
     300px;
    height: 300px;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
  }

  .wheel-pointer {
     60px;
    height: 60px;
    border-radius: 1000px;
    background: yellow;
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    line-height: 60px;
    z-index: 10;
    cursor: pointer;
  }

  .wheel-bg {
     100%;
    height: 100%;
    border-radius: 1000px;
    overflow: hidden;
    transition: transform 4s ease-in-out;
    background: #7EEF97;

    &.freeze {
      transition: none;
      background: red;
    }
  }

  .prize-list {
     100%;
    height: 100%;
    position: relative;
    text-align: center;
  }

  .prize-item-wrapper {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
     150px;
    height: 150px;
  }

  .prize-item {
     100%;
    height: 100%;
    transform-origin: bottom;

    .prize-name {
      padding: 16px 0;
    }

    .prize-icon {
    }
  }
</style>

随机数

     let rand = (function () {
        let today = new Date();
        let seed = today.getTime();

        function rnd() {
          seed = (seed * 9301 + 49297) % 233280;
          return seed / (233280.0);
        };
        return function rand(number) {
          return Math.ceil(rnd(seed) * number);
        };
      })();

      console.log(rand(100))
      console.log(rand(100))
      console.log(rand(100))