Introduction to the use of recursive functions in js-JS Tutorial-php.cn

Home

Web Front-end

JS Tutorial

Introduction to the use of recursive functions in js

黄舟

Dec 12, 2016 pm 02:41 PM

Let’s try a factorial within 10:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 
<title>js中递归函数的使用</title> 
<script type="text/javascript"> 
function f(num){ 
if(num<1){ 
return 1; 
}else{ 
return f(num-1)*num; 
} 
} 
</script> 
</head> 
<body> 
<script type="text/javascript"> 
alert("10!的结果为："+f(10)); 
</script> 
</body> 
</html>

Copy after login

That’s all for calling recursive functions

The insurance method when js recursive functions call themselves.
From js advanced programming
A typical factorial recursive function:

function fact(num){ 
if (num<=1){ 
return 1; 
}else{ 
return num*fact(num-1); 
} 
}

Copy after login

The following code can cause an error:
var anotherFact = fact;
fact = null;
alert(antherFact(4)); //Error

Because fact is no longer a function, an error occurred.
The problem can be solved with arguments.callee, which is a pointer to the function being executed.
The new function is:

function fact(num){ 
if (num<=1){ 
return 1; 
}else{ 
return num*arguments.callee(num-1); //此处更改了。 
} 
} 
var anotherFact = fact; 
fact = null; 
alert(antherFact(4)); //结果为24.

Copy after login

Improvements of ordinary recursion in JS

Recursive functions are formed when a function calls itself by name, as shown below:

function factorial(num) 
{ 
if(num<=1) 
{ 
return 1; 
} 
else
{ 
return num * factorial(num-1); 
} 
}

Copy after login

This is a classic factorial function. On the surface, there seems to be no problem, but the following code may cause it to go wrong.
var anotherFactory = factorial;

anotherFactorial(4); //Output 24
factorial = null;
anotherFacttorial (4); //TypeError: Property 'factorial' of object [object Window] is not a Test under function chrome
The reason is that the function name we defined is actually a pointer to the function, and anotherFacttorial is defined at this time It also points to that function, so calling anotherFactory (4) can successfully output 24
At this time factorial = null; Then the reference to the execution definition function is anotherFactorial, and the above error message will be displayed when calling anotherFactorial(4).
At this time, arguments.callee can be used to replace factorial in the function definition.
The definition of the function becomes:

function factorial(num) 
{ 
if(num<=1) 
{ 
return 1; 
} 
else
{ 
return num * arguments.callee(num-1); 
} 
}

Copy after login

Then using the above 4 lines of test code, the last line of test code can also successfully output 24.

Statement of this Website

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress images for free

Clothoff.io

AI clothes remover

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

What's New in Windows 11 KB5054979 & How to Fix Update Issues

3 weeks ago By DDD

How to fix KB5055523 fails to install in Windows 11?

2 weeks ago By DDD

InZoi: How To Apply To School And University

3 weeks ago By DDD

How to fix KB5055518 fails to install in Windows 10?

2 weeks ago By DDD

Roblox: Dead Rails – How To Summon And Defeat Nikola Tesla

4 weeks ago By 尊渡假赌尊渡假赌尊渡假赌

Hot Tools

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Hot Topics

Where is the login entrance for gmail email?

7817

Java Tutorial

1646

CakePHP Tutorial

1402

Laravel Tutorial

1300

PHP Tutorial

1238

Related knowledge

What should I do if I encounter garbled code printing for front-end thermal paper receipts? Apr 04, 2025 pm 02:42 PM

Frequently Asked Questions and Solutions for Front-end Thermal Paper Ticket Printing In Front-end Development, Ticket Printing is a common requirement. However, many developers are implementing...

Demystifying JavaScript: What It Does and Why It Matters Apr 09, 2025 am 12:07 AM

JavaScript is the cornerstone of modern web development, and its main functions include event-driven programming, dynamic content generation and asynchronous programming. 1) Event-driven programming allows web pages to change dynamically according to user operations. 2) Dynamic content generation allows page content to be adjusted according to conditions. 3) Asynchronous programming ensures that the user interface is not blocked. JavaScript is widely used in web interaction, single-page application and server-side development, greatly improving the flexibility of user experience and cross-platform development.

Who gets paid more Python or JavaScript? Apr 04, 2025 am 12:09 AM

There is no absolute salary for Python and JavaScript developers, depending on skills and industry needs. 1. Python may be paid more in data science and machine learning. 2. JavaScript has great demand in front-end and full-stack development, and its salary is also considerable. 3. Influencing factors include experience, geographical location, company size and specific skills.

How to merge array elements with the same ID into one object using JavaScript? Apr 04, 2025 pm 05:09 PM

How to merge array elements with the same ID into one object in JavaScript? When processing data, we often encounter the need to have the same ID...

Is JavaScript hard to learn? Apr 03, 2025 am 12:20 AM

Learning JavaScript is not difficult, but it is challenging. 1) Understand basic concepts such as variables, data types, functions, etc. 2) Master asynchronous programming and implement it through event loops. 3) Use DOM operations and Promise to handle asynchronous requests. 4) Avoid common mistakes and use debugging techniques. 5) Optimize performance and follow best practices.

How to achieve parallax scrolling and element animation effects, like Shiseido's official website? or: How can we achieve the animation effect accompanied by page scrolling like Shiseido's official website? Apr 04, 2025 pm 05:36 PM

Discussion on the realization of parallax scrolling and element animation effects in this article will explore how to achieve similar to Shiseido official website (https://www.shiseido.co.jp/sb/wonderland/)...

The Evolution of JavaScript: Current Trends and Future Prospects Apr 10, 2025 am 09:33 AM

The latest trends in JavaScript include the rise of TypeScript, the popularity of modern frameworks and libraries, and the application of WebAssembly. Future prospects cover more powerful type systems, the development of server-side JavaScript, the expansion of artificial intelligence and machine learning, and the potential of IoT and edge computing.

The difference in console.log output result: Why are the two calls different? Apr 04, 2025 pm 05:12 PM

In-depth discussion of the root causes of the difference in console.log output. This article will analyze the differences in the output results of console.log function in a piece of code and explain the reasons behind it. �...

See all articles