原生js练习

练习案例

某一刻时间距离现实时间的时间

function countDown(time) {
            var end = +new Date(time);
            var newDay = +new Date();
            var count_Down = Math.abs(end - newDay) / 1000; 
            // console.log(count_Down);

            var seconds = parseInt(count_Down % 60),
            minutes = parseInt(count_Down / 60 % 60),
            house = parseInt(count_Down /3600 % 60);
            let days = parseInt(count_Down/(3600*24)%24)
            console.log(days)

            seconds = seconds < 10 ? '0' + seconds : seconds;
            minutes = minutes < 10 ? '0' + minutes : minutes;
            house = house < 10 ? '0' + house : house;
            
            return ('事件间隔' + days + '天' + house + '小时' + minutes + '分钟' + seconds + '秒');
            
        }

console.log(countDown('2022-7-17 12:00:00'))
// 如果距离的在60分钟内的 算分钟数目 可以用 毫秒差值计算 absdt代表毫秒差
let min = new Date(absdt).getMinutes() // 条件在 absdt/1000 

冒泡排序

//冒泡排序 从大到小
function bubble_sort(ar) {
  var exc = 0;
  for(var i = 0; i < ar.length; i++) {
    for(var j = 0; j <  ar.length-1-i; j++) {
      if(ar[j] < ar[j+1]) {
        exc = ar[j];
        ar[j] = ar[j+1];
        ar[j+1] = exc;
      }
    }
  }
  console.log(ar);
}



//从大到小的冒泡排序
function bubbleSort() {
  for(var i = 0; i < arguments.length; i++) {
    for(var j = 0; j < arguments.length - i; j++) {
      if(arguments[j] > arguments[j + 1]) {
        var exc = 0;
        exc = arguments[j];
        arguments[j] = arguments[j + 1];
        arguments[j + 1] = exc;
      }
    }
  }
  return arguments;
}

简单计算器

// 简单计算器

function plush(one,two) {
  var sum = 0;
  sum = Number(one) + Number(two);
  return sum;
}
function lower(one,two) {
  var result = 0;
  result = one - two;
  return result;
}
function multiply(one,two) {
  var result = one * two;
  return result;
}
function remove(one,two) {
  var result = one / two;
  return result;
}
var num = prompt('欢迎使用简单计算器：/n 1.加法运算; /n 2.减法运算; /n 3.乘法运算 /n 4.乘法运算 /n 5.退出 /n 请输入您的选项');
var result;
while(num <= 5) {
  if(num == 5) {
    break;
  }
  var one = prompt('输入one'),two = prompt('输入two');
  switch(num) {
    case '1': 
      result = plush(one,two);
      alert('结果是：'+result);
      break;
    case '2': 
      result = lower(one,two);
      alert('结果是：'+result);
      break;
    case '3': 
      result = multiply(one,two);
      alert('结果是：'+result);
      break;
    case '4': 
      result = remove(one,two);
      alert('结果是：'+result);
      break;
    default : break;
  }
  num = prompt('欢迎使用简单计算器：/n 1.加法运算; /n 2.减法运算; /n 3.乘法运算 /n 4.乘法运算 /n 5.退出 /n 请输入您的选项');

}

随机点名

  // 随机点名
        var names = ['张三','张二','张一'];
        var i = Math.floor(Math.random() * names.length);
        console.log(i);
        console.log(names[i]);


        // 随机生成一个1-10的数字，并让用户输入一个数字
        var num = prompt('输入一个1-10数字');
        var rand = Math.floor(Math.random() * 10) + 1;
        console.log(rand);
        while(num != rand) {
            if(num > rand) {
                num = prompt('数字大了');
            }
            else {
                num = prompt('数字小了');
            }
        }
        alert('猜对了');

数组去重

var arr = ['c','a','z','a','x','c','b','c'];
function deWeight(arr) {
  var arrs = [];
  for(var i = 0; i < arr.length; i++) {
    if(arrs.indexOf(arr[i]) == -1) {
      arrs.unshift(arr[i]);
    }
  }
  return arrs;
}
console.log(deWeight(arr));

小练习

//将数组中大于10的元素选择出来
var ar = [2,0,6,1,77,0,52,0,25,7];
var ars = [];
for(var i = 0; i < ar.length; i++) {
  if(ar[i] > 10) {
    ars[ars.length] = ar[i];
  }
}
console.log(ars);


//去0
var ar = [2,0,6,1,77,0,52,0,25,7];
var ars = [];
for(var i = 0; i < ar.length; i++) {
  if(ar[i] != 0) {
    ars[ars.length] = ar[i];
  }
}
console.log(ars);

//数组中的元素倒过来存储
var ar = [2,0,6,1,77,0,52,0,25,7];
var ars = [];
for(var i = ar.length-1; i >= 0; i--) {
  ars[ars.length] = ar[i];
}
console.log(ars);




// 利用函数求任意个数的最大值
function maxValue() {
  var max = arguments[0];
  for(var i = 1; i < arguments.length; i++) {
    if(max < arguments[i]) {
      max = arguments[i];
    }
  }
  return max;
}

//翻转数组
function overTrue(ar) {
  var arrs = [];
  for(var i = ar.length-1; i >= 0; i--) {
    arrs[arrs.length] = ar[i];
  }
  return arrs;
} 
var a = [45,56,10,34,5,3];
console.log(overTrue(a));


// 判断闰年还是平年
function year_def(year) {
  if(year % 4 == 0 || year % 400 == 0) {
    return '闰年';
  }
  else {
    return '平年';
  }
}