How to determine whether numbers are equal in js-JS Tutorial-php.cn

Home

Web Front-end

JS Tutorial

How to determine whether numbers are equal in js

藏色散人

Mar 02, 2021 am 10:46 AM

JS method to determine the equality of numbers: first create an HTML sample file; then add a script tag; finally determine the number through "document.getElementById("demo").innerHTML = (x == 8);" Whether they are equal or not is enough.

How to determine whether numbers are equal in js

The operating environment of this article: Windows 7 system, JavaScript version 1.8.5, Dell G3 computer.

In JavaScript, you can directly use the comparison operator "==" to compare whether two numbers are equal. When comparing numbers with numbers, you cannot put 0 in front of it because 0 represents an octal number in the program.

1. JavaScript determines whether the numbers are equal.

console.log(012==12);  //false
console.log(012==10);  // true
console.log(099==99);  //true 这种情况是因为八进制中不可能出现9，所以看成一个十进制
console.log(09==9);    //true 同上

Example:

<!DOCTYPE html>
<html>
<body>
<h1 id="JavaScript比较">JavaScript比较</h1>
<p>把 5 赋值给 x，然后显示比较 (x == 8) 的值：</p>
<p id="demo"></p>
<script>
var x = 5;
document.getElementById("demo").innerHTML = (x == 8);
</script>
</body>
</html>

Running results:

How to determine whether numbers are equal in js

##[Recommended video tutorial:

js basic tutorial]

JavaScript compares whether two values are equal:

2. Under normal circumstances, convert both sides into number type data as much as possible, and then compare, rather than converting to Boolean type

console.log(true==2);   // false

If both sides are converted to Boolean type and then compared, then true==true and false will not be returned, so it proves that it is not both sides that are converted to Boolean type and then compared! ! It should be that both sides are converted to number type, 1==2, and false

console.log(true==1);   // true

3, underfined, null, 0, NaN, and "" will all become false when converted to Boolean values, then How does it perform in "=="?

①Underfined and null

Undefined and null return false when compared with any meaningful value. Null and undefined are equal to other numbers in the operation No type conversion is performed, but null==undefined

console.log(null==undefined);  //true  
console.log(null===undefined);  //false ===: 全等：不仅比较值是否相等，数据类型要相同
console.log(null==0);          // false
console.log(undefined==1);     //false
console.log(null==false);       // false
console.log(undefined=="");     // false

The above is the detailed content of How to determine whether numbers are equal in js. For more information, please follow other related articles on the PHP Chinese website!

Statement

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

Python vs. JavaScript: A Comparative Analysis for DevelopersMay 09, 2025 am 12:22 AM

The main difference between Python and JavaScript is the type system and application scenarios. 1. Python uses dynamic types, suitable for scientific computing and data analysis. 2. JavaScript adopts weak types and is widely used in front-end and full-stack development. The two have their own advantages in asynchronous programming and performance optimization, and should be decided according to project requirements when choosing.

Python vs. JavaScript: Choosing the Right Tool for the JobMay 08, 2025 am 12:10 AM

Whether to choose Python or JavaScript depends on the project type: 1) Choose Python for data science and automation tasks; 2) Choose JavaScript for front-end and full-stack development. Python is favored for its powerful library in data processing and automation, while JavaScript is indispensable for its advantages in web interaction and full-stack development.

Python and JavaScript: Understanding the Strengths of EachMay 06, 2025 am 12:15 AM

Python and JavaScript each have their own advantages, and the choice depends on project needs and personal preferences. 1. Python is easy to learn, with concise syntax, suitable for data science and back-end development, but has a slow execution speed. 2. JavaScript is everywhere in front-end development and has strong asynchronous programming capabilities. Node.js makes it suitable for full-stack development, but the syntax may be complex and error-prone.

JavaScript's Core: Is It Built on C or C ?May 05, 2025 am 12:07 AM

JavaScriptisnotbuiltonCorC ;it'saninterpretedlanguagethatrunsonenginesoftenwritteninC .1)JavaScriptwasdesignedasalightweight,interpretedlanguageforwebbrowsers.2)EnginesevolvedfromsimpleinterpreterstoJITcompilers,typicallyinC ,improvingperformance.

JavaScript Applications: From Front-End to Back-EndMay 04, 2025 am 12:12 AM

JavaScript can be used for front-end and back-end development. The front-end enhances the user experience through DOM operations, and the back-end handles server tasks through Node.js. 1. Front-end example: Change the content of the web page text. 2. Backend example: Create a Node.js server.

Python vs. JavaScript: Which Language Should You Learn?May 03, 2025 am 12:10 AM

Choosing Python or JavaScript should be based on career development, learning curve and ecosystem: 1) Career development: Python is suitable for data science and back-end development, while JavaScript is suitable for front-end and full-stack development. 2) Learning curve: Python syntax is concise and suitable for beginners; JavaScript syntax is flexible. 3) Ecosystem: Python has rich scientific computing libraries, and JavaScript has a powerful front-end framework.

JavaScript Frameworks: Powering Modern Web DevelopmentMay 02, 2025 am 12:04 AM

The power of the JavaScript framework lies in simplifying development, improving user experience and application performance. When choosing a framework, consider: 1. Project size and complexity, 2. Team experience, 3. Ecosystem and community support.

The Relationship Between JavaScript, C , and BrowsersMay 01, 2025 am 12:06 AM

Introduction I know you may find it strange, what exactly does JavaScript, C and browser have to do? They seem to be unrelated, but in fact, they play a very important role in modern web development. Today we will discuss the close connection between these three. Through this article, you will learn how JavaScript runs in the browser, the role of C in the browser engine, and how they work together to drive rendering and interaction of web pages. We all know the relationship between JavaScript and browser. JavaScript is the core language of front-end development. It runs directly in the browser, making web pages vivid and interesting. Have you ever wondered why JavaScr

See all articles