How to subscribe to events (topic created, topic closed, etc..)

Development
3

What is the best way to find them? I’m searching for onAppEvent but that isn’t turning up much:

$ grep -r onAppEvent *
app/assets/javascripts/discourse/lib/plugin-api.js.es6:    this.onAppEvent("page:changed", data => fn(data.url, data.title));
app/assets/javascripts/discourse/lib/plugin-api.js.es6:      api.onAppEvent('inserted-custom-html', () => {
app/assets/javascripts/discourse/lib/plugin-api.js.es6:  onAppEvent(name, fn) {
jsapp/lib/plugin-api.js.es6:    this.onAppEvent("page:changed", data => fn(data.url, data.title));
jsapp/lib/plugin-api.js.es6:      api.onAppEvent('inserted-custom-html', () => {
jsapp/lib/plugin-api.js.es6:  onAppEvent(name, fn) {