A system is registered similarly to a A-Frame component.
If the system name matches a component name, then the component will have a reference to the system as this.system:
AFRAME.registerSystem('my-component', {
schema: {}, // System schema. Parses into `this.data`.
init: function () {
// Called on scene initialization.
},
// Other handlers and methods.
});
AFRAME.registerComponent('my-component', {
init: function () {
console.log(this.system);
}
});