TrustedTypePolicyFactory: isHTML() method

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Note: This feature is available in Web Workers.

The isHTML() method of the TrustedTypePolicyFactory interface returns true if it is passed a valid TrustedHTML object.

Note: The purpose of the functions isHTML(), isScript(), and isScriptURL() is to check if the object is a valid TrustedType object, created by a configured policy.

Syntax

isHTML(value)

Return value

A boolean that is true if the object is a valid TrustedHTML object.

In the below example the constant html was created by a policy, and therefore isHTML() returns true. The second example is an attempt to fake an object, and the third is a string. Both of these will return false when passed to isHTML().

const html = policy.createHTML("<div>");
console.log(trustedTypes.isHTML(html)); // true;

const fake = Object.create(TrustedHTML.prototype);
console.log(trustedTypes.isHTML(fake)); // false

console.log(trustedTypes.isHTML("<div>plain string</div>")); // false