You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
29 lines
570 B
29 lines
570 B
3 years ago
|
var EventEmitter = require('events').EventEmitter
|
||
|
|
|
||
|
|
function Counter () {
|
||
|
|
EventEmitter.call(this)
|
||
|
|
this.value = 0
|
||
|
|
}
|
||
|
|
|
||
|
|
Counter.prototype = Object.create(EventEmitter.prototype)
|
||
|
|
|
||
|
|
Counter.prototype.increment = function increment () {
|
||
|
|
this.value++
|
||
|
|
}
|
||
|
|
|
||
|
|
Counter.prototype.decrement = function decrement () {
|
||
|
|
if (--this.value === 0) this.emit('zero')
|
||
|
|
}
|
||
|
|
|
||
|
|
Counter.prototype.isZero = function isZero () {
|
||
|
|
return (this.value === 0)
|
||
|
|
}
|
||
|
|
|
||
|
|
Counter.prototype.onceZero = function onceZero (fn) {
|
||
|
|
if (this.isZero()) return fn()
|
||
|
|
|
||
|
|
this.once('zero', fn)
|
||
|
|
}
|
||
|
|
|
||
|
|
module.exports = Counter
|