JavaScript-Based Policy

You can use this type of policy to define conditions for your permissions using JavaScript. It is one of the rule-based policy types supported by Keycloak, and provides flexibility to write any policy based on the Evaluation API.

To create a new JavaScript-based policy, select JavaScript in the dropdown list in the upper right corner of the policy listing.

Add JavaScript Policy

Add JavaScript Policy


  • Name

    A human-readable and unique string describing the policy. A best practice is to use names that are closely related to your business and security requirements, so you can identify them more easily.

  • Description

    A string containing details about this policy.

  • Code

    The JavaScript code providing the conditions for this policy.

  • Logic

    The Logic of this policy to apply after the other conditions have been evaluated.


Here is a simple example of a JavaScript-based policy that uses attribute-based access control (ABAC) to define a condition based on an attribute obtained from the execution context:

var context = $evaluation.getContext();
var contextAttributes = context.getAttributes();

if (contextAttributes.containsValue('', '')) {

You can also use role-based access control (RBAC):

var identity = $evaluation.getIdentity();

if (identity.hasRole('keycloak_user')) {

Or a combination of several access control mechanisms:

var context = $evaluation.getContext();
var identity = context.getIdentity();
var attributes = identity.getAttributes();
var email = attributes.getValue('email').asString(0);

if (identity.hasRole('admin') || email.endsWith('')) {

When writing your own rules, keep in mind that the $evaluation object is an object implementing org.keycloak.authorization.policy.evaluation.Evaluation. For more information about what you can access from this interface, see the Evaluation API.