Casbin.js

Casbin.js is the frontend library for Casbin, which facilitates the manipulation, management and storage of the user permission in a frontend application.

Example

We demonstrate the usage of Casbin.js with a React app. View the code to see more details.

You can use manual mode in Casbin.js, and set the permission whenever you wish.

const casbinjs = require('casbin.js');

// Set the user's permission:
// He/She can read 2 objects: data1 and data2
// Can write 1 objects: data1
const permission = {
    "read": ['data1', 'data2'],
    "write": ['data1']
}

// Run casbin.js in manual mode, which requires you to set the permission manually.
const authorizer = new casbinjs.Authorizer("manual");

authorizer.setPermission(permission);

authorizer.can("read", "data1").then(result => {
  console.log(result)
})
authorizer.cannot("write", "data2").then(result => {
  console.log(result)
});

In manual mode you can also pass the model and policies produced by the backend's CasbinJsGetPermissionForUser (a JSON object with the keys m, p and g) to setPermission. Casbin.js then builds a real enforcer from that data, so roles (g rules) are taken into account. Remember to set the user, since the request is evaluated as (user, object, action).

const authorizer = new casbinjs.Authorizer("manual");

// The JSON string or object returned by CasbinJsGetPermissionForUser
authorizer.setPermission(responseFromApi);
await authorizer.setUser("alice");

authorizer.can("read", "data1").then(result => {
  console.log(result)
});

Users with several roles

A user may hold any number of roles at the same time, and a role may inherit from another role. Casbin.js evaluates the g rules with the same RBAC engine as the backend, so the user gets the permissions of every one of those roles. This needs the model and policies described above: the plain {action: [objects]} map holds no roles at all, only the flattened result.

// g, alice, admin
// g, alice, editor
// g, admin, root
const authorizer = new casbinjs.Authorizer("manual");
authorizer.setPermission(responseFromApi);
await authorizer.setUser("alice");

// Granted by "admin", by "editor", and by the "root" role that "admin" inherits.
await authorizer.can("read", "data1");

// ["admin", "editor", "root"]
await authorizer.getRoles();

// [["admin", "data1", "read"], ["editor", "data2", "write"], ...]
await authorizer.getImplicitPermissions();

For a model with domains, pass the domain to each of them: authorizer.can("read", "data1", "domain1"), authorizer.getRoles("domain1").

You can also use the auto mode. In details, specify a casbin backend service endpoint when initializing the Casbin.js authorizer, and set the subject when the frontend user identity changes. Casbin.js will automatically fetch the permission from the endpoint. (A pre-configurated casbin service API is required at the backend.)

const casbinjs = require('casbin.js');

// Set your backend casbin service url
const authorizer = new casbinjs.Authorizer('auto', {endpoint: 'http://Domain_name/casbin/api'});

// When the identity shifts, reset the user. Casbin.js will automatically fetch the permission from the endpoint.
await authorizer.setUser("Tom");

// Evaluate the permission
authorizer.can("read", "data1").then();

More functionalities of Casbin.js are still under development. Feel free to raise issues to share your features suggestions!

TODO MAP

• Permission cache.
• Cookie mode.
• Lightweight enforcer (avoid the abuse of async functions).
• Integration with other modern frontend frameworks.