1.效果图：
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>Math.random方法彩票随机数的生成</title></head><body> <!-- 设置样式 --> <input type="text" id="text"> <button id="btnGo">开始</button> <button id="btnStop">获取随机数组</button> <script type="text/javascript"> //获取节点 var btnGo = document.getElementById("btnGo"); var btnStop = document.getElementById("btnStop"); var text = document.getElementById("text"); //定义生成最小到最大值的随机函数 function rand(min,max){ return parseInt(Math.random()*( max - min + 1) + min); } function start(min,max,length){ //定义空数组 var arr = []; while(arr.length<length){ //生成一个随机数prem var prem=rand(min,max); //判断生成的随机数prem是否在数组arr里,果然不在，就将这个随机数插入到数组里，如果在，执行下一次循环 if(arr.indexOf(prem) == -1){ arr.push(prem); } } //返回数组arr return arr; } var timer = 0; //单击开始按钮生成随机数组 btnGo.onclick =function(){ //清除 clearInterval(timer); timer = setInterval(function() { text.value = start(1,33,7); },50) } //单击停止按钮获取一组随机数 btnStop.onclick =function(){ clearInterval(timer); } </script></body></html>2.复杂版
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>Math.random方法彩票随机数的生成-升级版</title> <style type="text/css"> *{ margin: 0; padding: 0; } .wrap{ width: 600px; height: 300px; background-color: #f8e2e2; margin: 0 auto; } .list{ width: 440px; /*border: 1px solid red;*/ margin: 0px auto; } .list li{ list-style: none; width: 30px; height: 30px; display: inline-block; border: 1px solid #fff; border-radius: 30px; line-height: 30px; text-align: center; margin: 15px auto 15px; /*background-color: #f8f8f8;*/ /*background-color: rgba(255,255,255,1);*/ } .wrap p{ text-align: center; } .wrap p button{ text-align: center; width: 100px; } #setBtn{ background-color: red; color: #fff; border: none; } .active{ background-color: red; color: #fff; } </style></head><body> <div class="wrap" id="wrap"> <ul class="list"> <li>01</li> <li>02</li> <li>03</li> <li>04</li> <li>05</li> <li>06</li> <li>07</li> <li>08</li> <li>09</li> <li>10</li> <li>11</li> <li>12</li> <li>13</li> <li>14</li> <li>15</li> <li>16</li> <li>17</li> <li>18</li> <li>19</li> <li>20</li> <li>21</li> <li>22</li> <li>23</li> <li>24</li> <li>25</li> <li>26</li> <li>27</li> <li>28</li> <li>29</li> <li>30</li> <li>31</li> <li>32</li> <li>33</li> </ul> <p> <button id="setBtn">随机红球</button> <button id="clearBtn">清空</button> </p> </div> <script type="text/javascript"> var ballList = document.getElementById("wrap").getElementsByTagName("li"); var setBtn =document.getElementById("setBtn"); var clearBtn =document.getElementById("clearBtn"); //定义随机数组 function rnd(min, max) { return parseInt(Math.random()*(max - min + 1) + min); } function rndArray(min, max, length) { //先定义一个空数组 var arr = []; //生成一个长度为7的数组 while(arr.length < length) { //生成一个随机数 var rand = rnd(min, max); //判断生成的随机数rand是否在数组arr里,果然不在，就将这个随机数插入到数组里，如果在，执行下一次循环 if(arr.indexOf(rand) == -1) { arr.push(rand); } } arr.sort(function(a, b){return a - b;}) return arr; } function selectBall() { for(var j = 0; j < ballList.length; j++) { ballList[j].className = ""; } var arr = rndArray(1,33,7); // console.log(arr); for(var i = 0; i < arr.length; i++) { ballList[arr[i]-1].className = "active"; } } var timer = 0; setBtn.onclick = function() { clearTimeout(timer); timer = setInterval(selectBall,100); setTimeout(function() { clearTimeout(timer); },3000) // clearTimeout(timer); } clearBtn.onclick = function() { clearTimeout(timer); for(var j = 0; j < ballList.length; j++) { ballList[j].className = ""; } } </script></body></html>
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
