Method: 1. Use delete, the syntax "delete arr [delete the subscript of the element]"; 2. Use pop(), the syntax "arr.pop()"; 3. Use splice(), the syntax "arr.splice (starting position, number of deleted items)"; 4. Use the prototype prototype method.
The operating environment of this tutorial: Windows 7 system, JavaScript version 1.8.5, Dell G3 computer.
In JavaScript, besides Object, the Array type (array) is probably the most commonly used type. Arrays in JavaScript are very flexible compared to arrays in other languages. This kind of flexibility has advantages and disadvantages. The advantage is that it is creative and can provide various flexible solutions; the disadvantage is that it is easy to be brainless, because in fact, it is too flexible, and it is so flexible that it is uncontrollable and crazy.
After teasing a few words before, let’s get back to the topic. Here are 5 ways to delete Array elements in JavaScript, namely using the delete keyword, the pop() stack method, the shift() queue method, and splice( ) operation method and prototype prototype method.
delete keyword
JavaScript provides a delete
keyword to delete (clear) array elements.
var colors = ["red", "blue", "grey", "green"]; delete colors[0]; console.log(colors); // [undefined, "blue", "grey", "green"]
It should be noted that after using delete to delete an element, the length of the array remains unchanged, but the deleted element is set to undefined
.
pop() stack method
The Array object in JavaScript provides a pop()
stack method for popping and returning The last item in the array can be used as a deletion to some extent.
The access rule of the stack data structure is FILO
(first in, last out). The stack operation adds items to the top of the stack and removes items from the top of the stack. Use the pop() method, which can move Divides the last item in the array and returns that item, and reduces the length of the array by one.
var colors = ["red", "blue", "grey"]; var color = colors.pop(); console.log(color); // "grey" console.log(colors.length); // 2
It can be seen that when the pop() method is called, the array returns the last item, which is "grey", and there are only two elements left in the array.
splice() operation method
The JavaScript Array object provides a splice()
method for performing specific operations on the array. . splice() is probably the most powerful array method. It can be used in many ways. Here we only introduce the method of deleting array elements. When deleting array elements, it can delete any number of items by specifying only 2 parameters: the position of the first item to be deleted and the number of items to be deleted.
var colors = ["red", "blue", "grey"]; var color = colors.splice(0, 1); console.log(color); // "red" console.log(colors); // ["blue", "grey"]
It can be seen that when the splice(0, 1) method is called, one item is deleted from the array starting from the first item.
prototype prototype method
You can achieve the purpose of deletion by adding a method to the prototype of Array.
Array.prototype.remove = function(dx) { if(isNaN(dx) || dx > this.length){ return false; } for(var i = 0, n = 0; i < this.length; i++) { if(this[i] != this[dx]) { this[n++] = this[i]; } } this.length -= 1; }; var colors = ["red", "blue", "grey"]; colors.remove(1); console.log(colors); // ["red", "grey"]
This method is actually to implement a deletion logic by yourself, and then add the deletion method to the Array prototype object. Then all Array objects in this environment can use this method. Although it is possible to do so, it is not recommended to modify the prototype of a native object in a production application. The reason is simple. If a method is missing in a certain implementation, then adding this method to the prototype of the native object may lead to naming conflicts when the code is run in another implementation that supports this method. And doing so may accidentally cause native methods to be overridden.
shift() queue method
The Array object in JavaScript provides a shift()
queue method for popping and returning The first item in the array can also be used for deletion to some extent.
The access rule of the queue data structure is FIFO
(first in, first out). The queue adds items at the end of the list and removes items from the front of the list. Using the shift() method, it can Removes the first item in the array and returns it, decrementing the length of the array by one.
var colors = ["red", "blue", "grey"]; var color = colors.shift(); console.log(color); // "red" console.log(colors.length); // 2
It can be seen that when the shift() method is called, the array returns the first item, which is "red", and there are only two elements left in the array.
Relevant learning recommendations: javascript (video)
The above is the detailed content of How to delete array elements in javascript. For more information, please follow other related articles on the PHP Chinese website!

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.

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.


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

SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

Dreamweaver CS6
Visual web development tools

SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.

SublimeText3 Linux new version
SublimeText3 Linux latest version

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