国产av日韩一区二区三区精品,成人性爱视频在线观看,国产,欧美,日韩,一区,www.成色av久久成人,2222eeee成人天堂

Table of Contents
: Define the functions of sort order. It receives two parameters (a, b) and returns:
<不> Methods will not modify the original array.
Statue method
Example: Group data according to attributes
Home Web Front-end JS Tutorial JavaScript Array Methods: Sort, Map, Filter, and Reduce

JavaScript Array Methods: Sort, Map, Filter, and Reduce

Jan 29, 2025 am 02:30 AM

JavaScript Array Methods: Sort, Map, Filter, and Reduce

Master the JavaScript array method: sorting, mapping, filtering, and regulation to improve your web development efficiency! This article discusses the

, sort, map and filter methods of the JavaScript array, and provides practical examples to help you proficient in data processing. reduce

  1. Array.prototype.sort

    Sorting method

    2. Methods arrange array elements according to the specified order. By default, it sorted the string element in the sequential sequence of the dictionary. But through custom comparison functions, you can achieve more complicated sorting logic.

grammar sort

: Define the functions of sort order. It receives two parameters (a, b) and returns: 

array.sort([compareFunction])
Negative value: If A should be ranked before B.
  • Zero: If A and B are equal. compareFunction
      Positive value: If A should be ranked behind B.
    • Example: Sort the number in the sequential order
    • Example: Sort by attribute sorting object 

const numbers = [42, 7, 19, 73, 23];

numbers.sort((a, b) => a - b);

console.log(numbers); // 輸出：[7, 19, 23, 42, 73]
<會> Methods modify the original array.

For numbers or complex sorting, it is necessary to provide a comparison function to avoid accidents. 
const books = [
  { title: 'Book A', year: 2001 },
  { title: 'Book B', year: 1998 },
  { title: 'Book C', year: 2015 }
];

books.sort((a, b) => a.year - b.year);

console.log(books); // 輸出：按年份升序排列的書籍?dāng)?shù)組
  • sort
    • Array.prototype.map
  • Map method
  1. <通過> Methods create a new array by applying the function provided to each element of the original array. It is often used in data conversion.

    grammar <語>

    2. <對>: For functions performed by each element, receive:

Current element. map

Elemental index.

Original array. 
array.map(callback(element, index, array))
  • callback
      Example: Convert the number array
    • Example: Formatal data
    <不> The method will not modify the original array, and it returns a new array.
It is very suitable for conversion of the data structure. 

const numbers = [1, 2, 3, 4, 5];

const squares = numbers.map(num => num ** 2);

console.log(squares); // 輸出：[1, 4, 9, 16, 25]

Array.prototype.filter 
const users = [
  { firstName: 'John', lastName: 'Doe' },
  { firstName: 'Jane', lastName: 'Smith' }
];

const fullNames = users.map(user => `${user.firstName} ${user.lastName}`);

console.log(fullNames); // 輸出：['John Doe', 'Jane Smith']
Filter method
  • map
    • <創(chuàng)> Create a new array, which only contains elements that meet the given conditions. It is often used to extract data subsets.
    • grammar <語>
  1. <確>: Determine whether it should contain a function (return True) or exclude (back false) elements.

    Example: Filter the even number

Example: Filter the object according to the condition

filter

<不> Methods will not modify the original array. 

array.filter(callback(element, index, array))
It is a powerful tool for extracting related data or cleaning up arrays.
  • callback
Array.prototype.Reduce

Statue method 

const numbers = [1, 2, 3, 4, 5, 6];

const evens = numbers.filter(num => num % 2 === 0);

console.log(evens); // 輸出：[2, 4, 6]

<將> The method applies a function to each element (from left to right) of the accumulator and array, and attributes it to a single value. 
const products = [
  { name: 'Laptop', price: 1200 },
  { name: 'Phone', price: 800 },
  { name: 'Tablet', price: 500 }
];

const expensiveProducts = products.filter(product => product.price > 700);

console.log(expensiveProducts); // 輸出：價格高于700的產(chǎn)品數(shù)組

grammar <語> 

array.sort([compareFunction])
    <對>: For the function of each element, the parameters are:
  • callback Cumulator.
    • Current element.
    • Index of the current element.
    • Original array.
    <>: The initial value of the accumulator (optional, but it is recommended).
  • initialValue Example: Seeking peace

Example: Group data according to attributes 

const numbers = [42, 7, 19, 73, 23];

numbers.sort((a, b) => a - b);

console.log(numbers); // 輸出：[7, 19, 23, 42, 73]

<非常> The method is very flexible and can generate array, objects or single values. 
const books = [
  { title: 'Book A', year: 2001 },
  { title: 'Book B', year: 1998 },
  { title: 'Book C', year: 2015 }
];

books.sort((a, b) => a.year - b.year);

console.log(books); // 輸出：按年份升序排列的書籍?dāng)?shù)組
    It is a powerful tool for custom conversion, data aggregation, etc.
  • reduce Always provide the initial value to obtain better predictability.
    • Method combination
  • By combining ,
    • , and
methods, the data processing efficiency can be optimized, especially when dealing with large data sets, avoid multiple iterations to improve performance.

Conclusion

JavaScript's map, filter, reduce, and

methods are critical for efficient and elegant data operations. Understanding their mechanisms and applications can help developers write more concise and easy -to -maintain code. Practice more and be proficient in these methods!

The above is the detailed content of JavaScript Array Methods: Sort, Map, Filter, and Reduce. For more information, please follow other related articles on the PHP Chinese website!

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

Undress AI Tool

Undress AI Tool

Undress images for free

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

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

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Java vs. JavaScript: Clearing Up the Confusion Java vs. JavaScript: Clearing Up the Confusion Jun 20, 2025 am 12:27 AM

Java and JavaScript are different programming languages, each suitable for different application scenarios. Java is used for large enterprise and mobile application development, while JavaScript is mainly used for web page development.

Javascript Comments: short explanation Javascript Comments: short explanation Jun 19, 2025 am 12:40 AM

JavaScriptcommentsareessentialformaintaining,reading,andguidingcodeexecution.1)Single-linecommentsareusedforquickexplanations.2)Multi-linecommentsexplaincomplexlogicorprovidedetaileddocumentation.3)Inlinecommentsclarifyspecificpartsofcode.Bestpractic

How to work with dates and times in js? How to work with dates and times in js? Jul 01, 2025 am 01:27 AM

The following points should be noted when processing dates and time in JavaScript: 1. There are many ways to create Date objects. It is recommended to use ISO format strings to ensure compatibility; 2. Get and set time information can be obtained and set methods, and note that the month starts from 0; 3. Manually formatting dates requires strings, and third-party libraries can also be used; 4. It is recommended to use libraries that support time zones, such as Luxon. Mastering these key points can effectively avoid common mistakes.

Why should you place tags at the bottom of the ? Why should you place tags at the bottom of the ? Jul 02, 2025 am 01:22 AM

PlacingtagsatthebottomofablogpostorwebpageservespracticalpurposesforSEO,userexperience,anddesign.1.IthelpswithSEObyallowingsearchenginestoaccesskeyword-relevanttagswithoutclutteringthemaincontent.2.Itimprovesuserexperiencebykeepingthefocusonthearticl

JavaScript vs. Java: A Comprehensive Comparison for Developers JavaScript vs. Java: A Comprehensive Comparison for Developers Jun 20, 2025 am 12:21 AM

JavaScriptispreferredforwebdevelopment,whileJavaisbetterforlarge-scalebackendsystemsandAndroidapps.1)JavaScriptexcelsincreatinginteractivewebexperienceswithitsdynamicnatureandDOMmanipulation.2)Javaoffersstrongtypingandobject-orientedfeatures,idealfor

JavaScript: Exploring Data Types for Efficient Coding JavaScript: Exploring Data Types for Efficient Coding Jun 20, 2025 am 12:46 AM

JavaScripthassevenfundamentaldatatypes:number,string,boolean,undefined,null,object,andsymbol.1)Numbersuseadouble-precisionformat,usefulforwidevaluerangesbutbecautiouswithfloating-pointarithmetic.2)Stringsareimmutable,useefficientconcatenationmethodsf

What is event bubbling and capturing in the DOM? What is event bubbling and capturing in the DOM? Jul 02, 2025 am 01:19 AM

Event capture and bubble are two stages of event propagation in DOM. Capture is from the top layer to the target element, and bubble is from the target element to the top layer. 1. Event capture is implemented by setting the useCapture parameter of addEventListener to true; 2. Event bubble is the default behavior, useCapture is set to false or omitted; 3. Event propagation can be used to prevent event propagation; 4. Event bubbling supports event delegation to improve dynamic content processing efficiency; 5. Capture can be used to intercept events in advance, such as logging or error processing. Understanding these two phases helps to accurately control the timing and how JavaScript responds to user operations.

How can you reduce the payload size of a JavaScript application? How can you reduce the payload size of a JavaScript application? Jun 26, 2025 am 12:54 AM

If JavaScript applications load slowly and have poor performance, the problem is that the payload is too large. Solutions include: 1. Use code splitting (CodeSplitting), split the large bundle into multiple small files through React.lazy() or build tools, and load it as needed to reduce the first download; 2. Remove unused code (TreeShaking), use the ES6 module mechanism to clear "dead code" to ensure that the introduced libraries support this feature; 3. Compress and merge resource files, enable Gzip/Brotli and Terser to compress JS, reasonably merge files and optimize static resources; 4. Replace heavy-duty dependencies and choose lightweight libraries such as day.js and fetch

See all articles