day4 #19
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输出数组中的最大值和最小值和平均值<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>14输出数组中的最大值和最小值和平均值</title>
<script>
/*
[10,2,8,55,32,18,9,11,30,16,19,20]
分别计算出以上数组的最大值，最小值和整个数组的平均值，并输出他们的索引
*/
// 遍历数组
var arr = [10,2,8,55,32,18,9,11,30,16,19,20];
// 先假设最大值和最小值
var maxIdx = 0;
var minIdx = 0;
var max = arr[0];
var min = arr[0];
var sum = arr[0];
for(var i=1;i<arr.length;i++){
// 找出最大值
// 遍历过程中当前数字大于max，则把当前数字赋值给max
if(arr[i] > max){
max = arr[i];
maxIdx = i;
}else if(arr[i] < min){
min = arr[i];
minIdx = i;
}
// 计算所有数值的和
sum += arr[i];
}
var average = sum/arr.length;
console.log(maxIdx,max);
console.log(minIdx,min);
console.log('平均值：',average);
</script>
</head>
<body>
</body>
</html> |
随机点名<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>03随机点名简单版</title>
<script>
window.onload = function(){
//0 - arr.length-1
var arr = ['何国荣','黄耀华','司徒健伟','洪斌','黄博霖','肖清琳','杜凡','方洋','顾伟淘','胡子荣','谢孟宁','蒋涛','陈志权','谢霖辉','谢坤裕','梁喜龙','雷燕豪','江启民','胡泽浩'];
var name = document.getElementById('name');
var btn = document.getElementById('btnDM');
btn.onclick = function(){
// 得到一个随机整数
var idx = parseInt(Math.random()*arr.length);
// 把取到的名字写入#name输入框
name.value = arr[idx];
}
}
</script>
</head>
<body>
<input type="text" id="name">
<button id="btnDM">随机点名</button>
</body>
</html> |
数组的复制<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>08数组的复制</title>
<script>
var num = 20;
var res = num;
num = 100;
// console.log(num,res);
// 数据类型
// 引用数据类型：数组，对象
var arr = [10,20,30];
var arr2 = arr;
arr.push(100);
console.log(arr2,arr===arr2);//[10,20,30]
// 复制一个数组
var arr = ['广州','深圳','北京','上海'];
var city = [];
// 遍历arr中的每一项,把每个城市写入city数组
for(var i=0;i<arr.length;i++){
city[i] = arr[i];
}
console.log(city,arr,arr===city);//false;
function show(ar){
// var ar = city
ar.push('杭州')
}
show(city);
console.log('city:',city);
</script>
</head>
<body>
</body>
</html> |
创建一个包含50个三位数的随机数组<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>创建一个包含50个三位数的随机数组</title>
<script>
var arr = [];
// for循环添加元素
// 100-999
var arr = [];
for(var i=0;i<50;i++){
var num = parseInt(Math.random()*(999-100+1))+100;
arr[i] = num;
// arr[arr.length] = num;
//arr.push(num);
}
console.log(arr);
</script>
</head>
<body>
</body>
</html> |
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冒泡排序
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