Sharing solutions to cross-domain problems in JavaScript
This article mainly introduces relevant information about javascript cross-domain problems and solutions. Friends in need can refer to
javascript cross-domain problems and solutions
What is a cross-domain problem?
This cross-domain problem is caused by the same origin policy of the browser. The requested URL address must be the same protocol, the same domain name, and the same port as the browser URL, otherwise it is not allowed. Visited
| Browser URL | To be visited | Result |
|---|---|---|
| http://www.123.com/index | http://www.123.com/server | Success |
| http://www.123.com/index | http://www.456.com/server | Domain names are different, cross-domain |
| http://www.123.com:8080/index | http://www.123.com:8888/index.htm | The ports are different, Cross-domain |
| http://www.123.com/index | https://www.123.com/index | The protocols are different , Cross-domain |
Solution
Any tag with the src attribute can cross-domain, such as script, img, and iframe tags
JSONP
JSONP is the application of script tags. The full name of JSONP is JSON With Padding. JSONP consists of two parts. Return function and data. Return function is The function that should be called in the page when the response comes. The name of the callback function is specified in the request, and the data is the JSON data passed into the callback function
Example:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
function jsonCallback(data){
alert(data);
};
var url = "http://localhost:8888/test?callback=jsonCallback";
var script = document.createElement('script');
script.type = "text/javascript";
script.setAttribute('src', url);
document.getElementsByTagName('head')[0].appendChild(script);
</script>
</head>
<body>
</body>
</html>Disadvantages: It is not easy to confirm whether the JSONP request failed
Security issues, JSONP loads code from other domains for execution, so its reliability must be determined
Causes of cross-domain problems
Cross-domain problems are restricted by the browser's same-origin policy. The js of the current domain name can only read the window attributes in the same domain.
Scenarios where cross-domain problems occur
When you use js in a page to obtain data from other websites, cross-domain problems will occur, such as using ajax in the website to request data from other websites. When requesting data from weather, express or other data interfaces and hybrid apps, the browser will prompt the following error. In this scenario, it is necessary to solve the cross-domain problem of js.
XMLHttpRequest cannot load http://你请求的域名. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://当前页的域名' is therefore not allowed access.
What situations will cause cross-domain problems
The URL of a website includes the protocol name, subdomain name, main domain name, and port number. For example, https://github.com/, where https is the protocol name, www is the subdomain name, github is the main domain name, and the port number is 80. When requesting data from a URL in the page, if the protocol name of this URL, If any of the subdomain names, main domain names, and port numbers are different, cross-domain problems will occur.
Even if the page request http://127.0.0.1:80/ is at http://localhost:80/, there will be cross-domain problems
Solving cross-domain problems
Solving cross-domain problems The domain problem has the following method
Use jsonp
server proxy
The server sets the Access-Control-Allow-Origin in the Request Header to specify the domain name that can obtain data
jsonp’s solution
json≠jsonp
Principle
The principle of jsonp to solve cross-domain problems is that the browser’s script tag is not restricted by the same-origin policy (you You can set the src attribute of the script in your web page to ask the path of the static file in the CDN server). Then you can use the script tag to get data from the server. When requesting, add a parameter called callbakc=?, where the number ? is the callback method you want to execute.
The above is the detailed content of Sharing solutions to cross-domain problems in JavaScript. For more information, please follow other related articles on the PHP Chinese website!
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
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
How to implement an online speech recognition system using WebSocket and JavaScript
Dec 17, 2023 pm 02:54 PM
How to use WebSocket and JavaScript to implement an online speech recognition system Introduction: With the continuous development of technology, speech recognition technology has become an important part of the field of artificial intelligence. The online speech recognition system based on WebSocket and JavaScript has the characteristics of low latency, real-time and cross-platform, and has become a widely used solution. This article will introduce how to use WebSocket and JavaScript to implement an online speech recognition system.
Recommended: Excellent JS open source face detection and recognition project
Apr 03, 2024 am 11:55 AM
Face detection and recognition technology is already a relatively mature and widely used technology. Currently, the most widely used Internet application language is JS. Implementing face detection and recognition on the Web front-end has advantages and disadvantages compared to back-end face recognition. Advantages include reducing network interaction and real-time recognition, which greatly shortens user waiting time and improves user experience; disadvantages include: being limited by model size, the accuracy is also limited. How to use js to implement face detection on the web? In order to implement face recognition on the Web, you need to be familiar with related programming languages and technologies, such as JavaScript, HTML, CSS, WebRTC, etc. At the same time, you also need to master relevant computer vision and artificial intelligence technologies. It is worth noting that due to the design of the Web side
WebSocket and JavaScript: key technologies for implementing real-time monitoring systems
Dec 17, 2023 pm 05:30 PM
WebSocket and JavaScript: Key technologies for realizing real-time monitoring systems Introduction: With the rapid development of Internet technology, real-time monitoring systems have been widely used in various fields. One of the key technologies to achieve real-time monitoring is the combination of WebSocket and JavaScript. This article will introduce the application of WebSocket and JavaScript in real-time monitoring systems, give code examples, and explain their implementation principles in detail. 1. WebSocket technology
Essential tools for stock analysis: Learn the steps to draw candle charts with PHP and JS
Dec 17, 2023 pm 06:55 PM
Essential tools for stock analysis: Learn the steps to draw candle charts in PHP and JS. Specific code examples are required. With the rapid development of the Internet and technology, stock trading has become one of the important ways for many investors. Stock analysis is an important part of investor decision-making, and candle charts are widely used in technical analysis. Learning how to draw candle charts using PHP and JS will provide investors with more intuitive information to help them make better decisions. A candlestick chart is a technical chart that displays stock prices in the form of candlesticks. It shows the stock price
How to use JavaScript and WebSocket to implement a real-time online ordering system
Dec 17, 2023 pm 12:09 PM
Introduction to how to use JavaScript and WebSocket to implement a real-time online ordering system: With the popularity of the Internet and the advancement of technology, more and more restaurants have begun to provide online ordering services. In order to implement a real-time online ordering system, we can use JavaScript and WebSocket technology. WebSocket is a full-duplex communication protocol based on the TCP protocol, which can realize real-time two-way communication between the client and the server. In the real-time online ordering system, when the user selects dishes and places an order
JavaScript and WebSocket: Building an efficient real-time weather forecasting system
Dec 17, 2023 pm 05:13 PM
JavaScript and WebSocket: Building an efficient real-time weather forecast system Introduction: Today, the accuracy of weather forecasts is of great significance to daily life and decision-making. As technology develops, we can provide more accurate and reliable weather forecasts by obtaining weather data in real time. In this article, we will learn how to use JavaScript and WebSocket technology to build an efficient real-time weather forecast system. This article will demonstrate the implementation process through specific code examples. We
PHP and JS Development Tips: Master the Method of Drawing Stock Candle Charts
Dec 18, 2023 pm 03:39 PM
With the rapid development of Internet finance, stock investment has become the choice of more and more people. In stock trading, candle charts are a commonly used technical analysis method. It can show the changing trend of stock prices and help investors make more accurate decisions. This article will introduce the development skills of PHP and JS, lead readers to understand how to draw stock candle charts, and provide specific code examples. 1. Understanding Stock Candle Charts Before introducing how to draw stock candle charts, we first need to understand what a candle chart is. Candlestick charts were developed by the Japanese
Simple JavaScript Tutorial: How to Get HTTP Status Code
Jan 05, 2024 pm 06:08 PM
JavaScript tutorial: How to get HTTP status code, specific code examples are required. Preface: In web development, data interaction with the server is often involved. When communicating with the server, we often need to obtain the returned HTTP status code to determine whether the operation is successful, and perform corresponding processing based on different status codes. This article will teach you how to use JavaScript to obtain HTTP status codes and provide some practical code examples. Using XMLHttpRequest
