


JavaScript hasOwnProperty() function (picture and text tutorial, with code examples)
hasOwnProperty() function is used to indicate whether an object itself (excluding the prototype chain) has a property with the specified name. Let’s share with you an example of the JavaScript hasOwnProperty() function through this article. Friends who are interested should take a look
hasOwnProperty()
The function is used to indicate an object itself (excluding the prototype chain) Whether there is an attribute with the specified name. If there is, return true, otherwise return false.
This method belongs to the Object object. Since all objects "inherit" the object instance of Object, almost all instance objects can use this method.
Major browsers such as IE 5.5, FireFox, Chrome, Safari, and Opera all support this function.
Syntax
object.hasOwnProperty( propertyName )
Parameters
Parameters | Description |
---|---|
propertyName | String type Specified property name |
返回值
hasOwnProperty()
函数的返回值为Boolean类型。如果对象object具有名称为propertyName
的属性,则返回true,否则返回false。
此方法不会检查对象的原型链中是否存在该属性,该属性只有是对象本身的一个成员才会返回true。
示例&说明
function Site(){ this.name = "CodePlayer"; this.url = "http://www.365mini.com/"; this.sayHello = function(){ document.writeln("欢迎来到" + this.name); }; } var obj = { engine: "PHP" ,sayHi: function(){ document.writeln("欢迎访问" + this.url); } }; // 使用对象obj覆盖Site本身的prototype属性 Site.prototype = obj; var s = new Site(); document.writeln( s.hasOwnProperty("name") ); // true document.writeln( s.hasOwnProperty("sayHello") ); // true // 以下属性继承自原型链,因此为false document.writeln( s.hasOwnProperty("engine") ); // false document.writeln( s.hasOwnProperty("sayHi") ); // false document.writeln( s.hasOwnProperty("toString") ); // false // 想要查看对象(包括原型链)是否具备指定的属性,可以使用in操作符 document.writeln( "engine" in s ); // true document.writeln( "sayHi" in s ); // true document.writeln( "toString" in s ); // true
上面是我整理给大家的,希望今后会对大家有帮助。
相关文章:
JavaScript isPrototypeOf和hasOwnProperty使用区别(实用)
重点讲解在JavaScript中的__proto__属性(图文教程)
The above is the detailed content of JavaScript hasOwnProperty() function (picture and text tutorial, with code examples). For more information, please follow other related articles on the PHP Chinese website!

Both Python and JavaScript's choices in development environments are important. 1) Python's development environment includes PyCharm, JupyterNotebook and Anaconda, which are suitable for data science and rapid prototyping. 2) The development environment of JavaScript includes Node.js, VSCode and Webpack, which are suitable for front-end and back-end development. Choosing the right tools according to project needs can improve development efficiency and project success rate.

Yes, the engine core of JavaScript is written in C. 1) The C language provides efficient performance and underlying control, which is suitable for the development of JavaScript engine. 2) Taking the V8 engine as an example, its core is written in C, combining the efficiency and object-oriented characteristics of C. 3) The working principle of the JavaScript engine includes parsing, compiling and execution, and the C language plays a key role in these processes.

JavaScript is at the heart of modern websites because it enhances the interactivity and dynamicity of web pages. 1) It allows to change content without refreshing the page, 2) manipulate web pages through DOMAPI, 3) support complex interactive effects such as animation and drag-and-drop, 4) optimize performance and best practices to improve user experience.

C and JavaScript achieve interoperability through WebAssembly. 1) C code is compiled into WebAssembly module and introduced into JavaScript environment to enhance computing power. 2) In game development, C handles physics engines and graphics rendering, and JavaScript is responsible for game logic and user interface.

JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

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.


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

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

WebStorm Mac version
Useful JavaScript development tools

Atom editor mac version download
The most popular open source editor

EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.
