TrustedTypePolicy

The TrustedTypePolicy interface of the Trusted Types API defines a group of functions which create TrustedType objects.

A TrustedTypePolicy object is created by TrustedTypePolicyFactory.createPolicy() to define a policy for enforcing security rules on input. Therefore, TrustedTypePolicy has no constructor.

TrustedTypePolicy.nameRead only

A DOMString containing the name of the policy.

TrustedTypePolicy.createHTML()

Creates a TrustedHTML object.

TrustedTypePolicy.createScript()

Creates a TrustedScript object.

TrustedTypePolicy.createScriptURL()

Creates a TrustedScriptURL object.

In the below example we create a policy that will create TrustedHTML objects using TrustedTypePolicyFactory.createPolicy(). We can then use TrustedTypePolicy.createHTML to create a sanitized HTML string to be inserted into the document.

The sanitized value can then be used with Element.innerHTML to ensure that no new HTML elements can be injected.

<div id="myDiv"></div>

const escapeHTMLPolicy = trustedTypes.createPolicy("myEscapePolicy", {
  createHTML: (string) => string.replace(/\>/g, "<")
});

let el = document.getElementById("myDiv");
const escaped = escapeHTMLPolicy.createHTML("<img src=x onerror=alert(1)>");
console.log(escaped instanceof TrustedHTML); // true
el.innerHTML = escaped;