前端学习——jsDay4-编程知识

前端学习——jsDay4

函数

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函数使用

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小练习

<!DOCTYPE html>
<html lang="zh-CN">
<head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head>
<body><script>function hi(){document.write(`hi~`)}hi()</script>
</body>
</html>

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函数传参

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小练习

<!DOCTYPE html>
<html lang="zh-CN">
<head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head>
<body><script>function getsum(num1, num2){document.write(num1 + num2)}getsum(10,30)</script>
</body>
</html>

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小练习

<!DOCTYPE html>
<html lang="zh-CN"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head><body><script>let arr = [90, 85, 93, 100, 50, 60]function getsum(arr) {let sum = 0for (let i = 0; i < arr.length; i++) {sum += arr[i]}document.write(sum)}getsum(arr)</script>
</body></html>

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函数返回值

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小练习

<!DOCTYPE html>
<html lang="zh-CN"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head><body><script>function getmax(x, y) {if (y > x)return yelsereturn x}document.write(getmax(5, 10))</script>
</body></html>

<!DOCTYPE html>
<html lang="zh-CN"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head><body><script>function getmax(arr = []) {let max = 0for (let i = 0; i < arr.length; i++) {if (arr[i] > max)max = arr[i]}return max}document.write(getmax([5, 10, 50, 60]))</script>
</body></html>

<!DOCTYPE html>
<html lang="zh-CN"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head><body><script>function getmax(arr = []) {let max = arr[0]let min = arr[0]for (let i = 0; i < arr.length; i++) {if (arr[i] > max)max = arr[i]if (arr[i] < min)min = arr[i]}return [max, min]}document.write(getmax([5, 10, 50, 60]))</script>
</body></html>

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作用域

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a=4,b=22

匿名函数

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综合案例

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<!DOCTYPE html>
<html lang="zh-CN"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head><body><script>let input = prompt('请输入总秒数：')function bu0(a){if(a<10)a='0'+areturn a}function change(input){let h=parseInt(input/60/60%24)let m=parseInt(input/60%60)let s=parseInt(input%60)h=bu0(h)m=bu0(m)s=bu0(s)console.log(`${input}秒转化：${h}小时${m}分钟${s}秒`)}change(input)</script>
</body></html>