Using wp.apiRequest to access custom endpoints.

apiRequest.js

// See: wp-includes/js/api-request.js

// Returns a jqXHR object. See: https://api.jquery.com/jQuery.ajax/#jqXHR
wp.apiRequest({path: '/namespace/vendor/v1/config'})
    .then(configOptions => console.log(configOptions));

// jqXHR object has method then(), but does not have methods catch() or
// finally(). Use fail() or always() instead
wp.apiRequest({path: '/namespace/vendor/v1/config'})
    .done(configOptions => console.log(configOptions))
    .fail((request, statusText) => {
        if (request.responseJSON && request.responseJSON.message) {
            console.error(request.responseJSON.message);
        } else {
            console.error(statusText);
        }
    })
    always(() => console.log('Finish.'));

// Pass data to the request
wp.apiRequest({
    path: '/namespace/vendor/v1/entity',
    data: {
        id: 17
    }
})
    .then(...);

// By default the type of the request is "GET"
wp.apiRequest({
    path: '/namespace/vendor/v1/entity/delete',
    type: 'POST',
    data: {
        id: 17
    }
})
    .then(...);

/*
 * See also:
 *     https://api.jquery.com/jQuery.ajax/#data-types
 */