Awesome
nanobus
Tiny message bus.
Usage
var nanobus = require('nanobus')
var bus = nanobus()
bus.on('foo', function (color) {
console.log('color is', color)
})
bus.emit('foo', 'blue')
FAQ
Why not use the Node API?
We had the requirement for a *
event to catch all calls, and figured we could
improve the file size at the same time. This library is about 1/3rd the size of
Node's version. And it was easy to build, so yeah good enough of an excuse hah.
How do I listen for replies?
You can do this by using the .once()
listener and establishing a convention
around naming schemas.
bus.on('foo', function (color) {
console.log('foo called')
bus.emit('foo:res')
})
bus.once('foo:res', function () {
console.log('response received')
})
bus.emit('foo')
When shouldn't I use this package?
If you're only writing code that runs inside Node and don't need a '*'
listener, consider using the built-in event emitter API instead.
Are the emitters asynchronous?
No. If you're interested in doing that, use something like nanotick to batch events and ensure they run asynchronously.
API
bus = nanobus([name])
Create a new nanobus
instance. Optionally takes a name that will be used for
tracing in the browser using the performance.mark
/ performance.measure
API.
bus.emit(eventName, [data])
Emit an event. Arbitrary data can optionally be passed as an argument. '*'
listeners run after named listeners.
bus.on(eventName, listener([data]))
bus.addListener(eventName, listener([data]))
Listen to an event. If the event name is '*'
the listener signature is
listener(eventName, [data], [performanceTimingId])
.
bus.prependListener(eventName, listener([data]))
Listen to an event, but make sure it's pushed to the start of the listener
queue. If the event name is '*'
the listener signature is
listener(eventName, [data])
.
bus.once(eventName, listener([data]))
Listen to an event, and clear it after it's been called once. If the event
name is '*'
the listener signature is
listener(eventName, [data], [performanceTimingId])
.
bus.prependOnceListener(eventName, listener([data]))
Listen to an event, and clear it after it's been called once. If the event
name is '*'
the listener signature is listener(eventName, [data])
.
bus.removeListener(eventName, listener)
Remove a specific listener to an event.
listeners = bus.listeners(eventName)
Return all listeners for a given event. '*'
listeners are not included in
this list. Use bus.listeners('*')
to get a list of '*'
listeners.
bus.removeAllListeners([eventName])
Remove all listeners to an event. If no event name is passed, removes all
listeners on the message bus. '*'
listeners are not removed unless
eventName
is *
or no event name is passed.
TypeScript
Optional event typing is available in TypeScript by passing an object type with event names as keys and event listener function signatures as values.
// if compilerOptions.esModuleInterop = true
import Nanobus from "nanobus"
// else
import Nanobus = require("nanobus")
type Events = {
foo: (color: string) => void
bar: (count: number) => void
}
const bus = new Nanobus<Events>()
bus.on("foo", color => {
// color: string
console.log("color is", color)
})
bus.on("bar", count => {
// count: number
console.log("count is", count)
})
bus.on("*", (eventName, data) => {
// eventName: "foo" | "bar"
// data: any[]
if (eventName === "foo") {
const [color] = data as Parameters<Events["foo"]>
// color: string
} else if (eventName === "bar") {
const [count] = data as Parameters<Events["bar"]>
// count: number
}
})
bus.emit("foo", "blue") // required arguments: [string]
bus.emit("bar", 100) // required arguments: [number]