Introduction to the use of recursive functions in js_javascript skills
Let’s try a factorial within 10:
]
So much for calling recursive functions
The insurance method when js recursive functions call themselves.
From js advanced programming
function fact(num){
if (numreturn 1;
}else{
return num*fact(num-1);
}
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.
function fact(num ){
if (numreturn 1;
}else{
return num*arguments.callee(num-1); //Changed here.
}
}
var anotherFact = fact;
fact = null;
Improvements of ordinary recursion in JS
function factorial(num)
{
if(num{
return 1;
}
else
{
return num * factorial(num-1);
}
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 anotherFactorial = factorial;
anotherFactorial(4); //Output 24
factorial = null;
anotherFactorial (4); //TypeError: Property 'factorial' of object [object Window] is not a function. Test under chrome
The reason is that the function name we defined is actually a pointer to the function. At this time, anotherFactorial is defined and also points to that function, so calling anotherFactorial (4) can successfully output 24
At this time, factorial = null; then the reference of the execution definition function is anotherFactorial. Then the above error message will be displayed when calling anotherFactorial(4).
At this time, you can use arguments.callee to replace factorial in the function definition.
function factorial(num)
{
if(num{
return 1;
}
else
{
return num * arguments.callee(num-1);
}
Then use the above 4 lines of test code, The last line of test code can also be successfully output 24. ---------------------------------------- -- The above content is excerpted from section 7.1 on page 144 of the 2nd edition of >

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.

The shift from C/C to JavaScript requires adapting to dynamic typing, garbage collection and asynchronous programming. 1) C/C is a statically typed language that requires manual memory management, while JavaScript is dynamically typed and garbage collection is automatically processed. 2) C/C needs to be compiled into machine code, while JavaScript is an interpreted language. 3) JavaScript introduces concepts such as closures, prototype chains and Promise, which enhances flexibility and asynchronous programming capabilities.

Different JavaScript engines have different effects when parsing and executing JavaScript code, because the implementation principles and optimization strategies of each engine differ. 1. Lexical analysis: convert source code into lexical unit. 2. Grammar analysis: Generate an abstract syntax tree. 3. Optimization and compilation: Generate machine code through the JIT compiler. 4. Execute: Run the machine code. V8 engine optimizes through instant compilation and hidden class, SpiderMonkey uses a type inference system, resulting in different performance performance on the same code.

JavaScript's applications in the real world include server-side programming, mobile application development and Internet of Things control: 1. Server-side programming is realized through Node.js, suitable for high concurrent request processing. 2. Mobile application development is carried out through ReactNative and supports cross-platform deployment. 3. Used for IoT device control through Johnny-Five library, suitable for hardware interaction.


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

Hot Tools

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Atom editor mac version download
The most popular open source editor

Notepad++7.3.1
Easy-to-use and free code editor

Zend Studio 13.0.1
Powerful PHP integrated development environment