How to Unescape HTML Entities in JavaScript?

Unescaping HTML Entities in JavaScript

Issue Description

When retrieving XML-RPC strings containing HTML entities, JavaScript inserts them literally into HTML, preventing proper rendering. The text displays as a string rather than the intended HTML element.

Diagnosis and Solution

[DOMParser]

The preferred method for unescaping HTML entities in JavaScript is to use the DOMParser. DOMParser is a browser-supported tool that parses HTML strings and extracts their content. By using DOMParser, you can safely and effectively convert escaped entities into their corresponding characters.

Using DOMParser

The following function uses DOMParser to unescape HTML entities in JavaScript:

function htmlDecode(input) {
  var doc = new DOMParser().parseFromString(input, "text/html");
  return doc.documentElement.textContent;
}

Example

To demonstrate the function, we can unescape an HTML string containing an image entity:

console.log(  htmlDecode("<img src='myimage.jpg'>")  )    
// "<img src='myimage.jpg'>"

Security Considerations

Beware of potential Cross-Site Scripting (XSS) vulnerabilities if the input string is not trusted. Escaped HTML entities can hide malicious JavaScript code that may execute when the string is parsed.

Always validate user input before unescaping to prevent malicious actors from exploiting vulnerabilities.

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