Encoding libraries often have a EncodeForJavaScript or similar to support this function. When you are in a DOM execution context you only need to JavaScript encode HTML attributes which do not execute code (attributes other than event handler, CSS, and URL attributes). In general, HTML encoding serves to castrate HTML tags which are placed in HTML and HTML attribute contexts. This cheatsheet addresses DOM (Document Object Model) based XSS and is an extension (and assumes comprehension of) the XSS Prevention Cheatsheet. DOM-based XSS Examples. DOMPurify supports Trusted Types and will return sanitized HTML wrapped in a TrustedHTML object such that the browser does not generate a violation.CautionIf the sanitization logic in DOMPurify is buggy, your application might still have a DOM XSS vulnerability. There are other places in JavaScript where JavaScript encoding is accepted as valid executable code. Reflected and Stored XSS are server side injection issues while DOM based XSS is a client (browser) side injection issue. Generally, attributes that accept JavaScript, such as onClick, are NOT safe to use with untrusted attribute values. This is where Output Encoding and HTML Sanitization are critical. Note that browsers behave differently with regards to URL-encoding, Chrome, Firefox, and Safari will URL-encode location.search and location.hash, while IE11 and Microsoft Edge (pre-Chromium) will not URL-encode these sources. For JSON, verify that the Content-Type header is application/json and not text/html to prevent XSS. If you have to use user input on your page, always use it in the text context, never as HTML tags or any other potential code. Additionally, the website's scripts might perform validation or other processing of data that must be accommodated when attempting to exploit a vulnerability. Websites may also store data on the server and reflect it elsewhere. At a basic level XSS works by tricking your application into inserting a