Cross-Site Scripting, often abbreviated as XSS, is a type of security vulnerability that allows attackers to inject malicious scripts into web pages viewed by other users. A web application is vulnerable to XSS if it uses unsanitized user input in the output it generates.
ReactJS prevents Cross-Site Scripting (XSS) by design, as it escapes all variable that are rendered via curly braces ({}). When data is input directly into JSX, React automatically ensures that it is secured and prevents any malicious code from being executed.
ReactJS does this via two principles:
1. It escapes all variable content: ReactJS makes sure that all content is converted to a string before it gets rendered to the DOM. This way, even if the input looks like code, it does not get treated as such.
1. It doesn’t use innerHTML: Typically XSS attacks happen when you use data input directly inside innerHTML. ReactJS uses a faster and secure method of rendering to the DOM and does not rely on the use of innerHTML. Therefore, even if a user tried to embed HTML, JSX, or JavaScript inside inputs, React would safely display that as pure text, thereby preventing any XSS attack.
However, scenarios where this principle could be bypassed should still be handled carefully. Specifically, React’s built-in protection can be bypassed if a developer intentionally utilizes dangerous functions such as `dangerouslySetInnerHTML` or uses the user’s input to directly execute a script, set HTML attributes or URLs. So, even when using React, developers must still be aware of security best practices to ensure their application remains secure.
