1.随机函数代码

 function getRandom(min, max) {
        return Math.floor(Math.random() * (max - min + 1)) + min
      }

2.倒计时代码

      let now = +new Date()
      // 2. 得到指定时间的时间戳
      let last = +new Date('这里写想要达到的时间')
      // 3. （计算剩余的毫秒数） / 1000 === 剩余的秒数
      let count = (last - now) / 1000
      // console.log(count)
      // 4. 转换为时分秒
      // h = parseInt(总秒数 / 60 / 60 % 24)   //   计算小时
      let h = parseInt(count / 60 / 60 % 24)
      h = h < 10 ? '0' + h : h
      // m = parseInt(总秒数 / 60 % 60);     //   计算分数
      let m = parseInt(count / 60 % 60)
      m = m < 10 ? '0' + m : m
      // s = parseInt(总秒数 % 60); //   计算当前秒数
      let s = parseInt(count % 60);
      s = s < 10 ? '0' + s : s
      console.log(h, m, s)
      

3.精确显示时间代码

 let arr = ['星期日', '星期一', '星期二', '星期三', '星期四', '星期五', '星期六']
        let div = document.querySelector('div')
        // 先调用，就省去了1秒的空白期
        getTime()
        setInterval(getTime, 1000)
        function getTime() {
            // 1. 实例化时间对象 一定写到定时器里面才可以额
            let date = new Date()
            let year = date.getFullYear()
            let month = date.getMonth() + 1
            let date1 = date.getDate()
            let hour = date.getHours()
            let min = date.getMinutes()
            let sec = date.getSeconds()
            let day = date.getDay()
            div.innerHTML = `今天是： ${year}年${month}月${date1}日 ${hour}:${min}:${sec} ${arr[day]}`
        }

 4.鼠标滚动事件

$('#content').on("mousewheel DOMMouseScroll", function (event) { 
  // chrome & ie || // firefox
  var delta = (event.originalEvent.wheelDelta && (event.originalEvent.wheelDelta > 0 ? 1 : -1)) || (event.originalEvent.detail && (event.originalEvent.detail > 0 ? -1 : 1)); 
  
  if (delta > 0) { 
    // 向上滚动
    console.log('mousewheel top');
  } else if (delta < 0) {
    // 向下滚动
    console.log('mousewheel bottom');
  } 
});

5.js时间戳毫秒格式化 

function formatDate(now) { 
  var y = now.getFullYear();
  var m = now.getMonth() + 1; // 注意js里的月要加1 
  var d = now.getDate();
  var h = now.getHours(); 
  var m = now.getMinutes(); 
  var s = now.getSeconds();
  
  return y + "-" + m + "-" + d + " " + h + ":" + m + ":" + s; 
} 
var nowDate = new Date(2016, 5, 13, 19, 18, 30, 20);
console.log(nowDate.getTime()); // 获得当前毫秒数: 1465816710020
console.log(formatDate(nowDate));

 6.验证码倒计时

<!-- dom -->
<input id="send" type="button" value="发送验证码">

// 原生js版本
var times = 60, // 临时设为60秒
  timer = null;
      
document.getElementById('send').onclick = function () {
  // 计时开始
  timer = setInterval(function () {
    times--;
    
    if (times <= 0) {
      send.value = '发送验证码';
      clearInterval(timer);
      send.disabled = false;
      times = 60;
    } else {
      send.value = times + '秒后重试';
      send.disabled = true;
    }
  }, 1000);
}

// jQuery版本
var times = 60,
  timer = null;
$('#send').on('click', function () {
  var $this = $(this);
  
  // 计时开始
  timer = setInterval(function () {
    times--;
    
    if (times <= 0) {
      $this.val('发送验证码');
      clearInterval(timer);
      $this.attr('disabled', false);
      times = 60;
    } else {
      $this.val(times + '秒后重试');
      $this.attr('disabled', true);
    }
  }, 1000);
});

 7.获取到鼠标在页面的坐标

$('#myImage').click(function(event){
  //获取鼠标在图片上的坐标 
  console.log('X：' + event.offsetX+'\n Y:' + event.offsetY); 
  
  //获取元素相对于页面的坐标 
  console.log('X：'+$(this).offset().left+'\n Y:'+$(this).offset().top);
});

8.h5全屏

function fullscreen(element) {
  if (element.requestFullscreen) {
    element.requestFullscreen();
  } else if (element.mozRequestFullScreen) {
    element.mozRequestFullScreen();
  } else if (element.webkitRequestFullscreen) {
    element.webkitRequestFullscreen();
  } else if (element.msRequestFullscreen) {
    element.msRequestFullscreen();
  }
}

fullscreen(document.documentElement);

author：冰海恋雨