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Publish/Subscribe Pattern Implementation
var events = {
events: {},
subscribe: function (eventName, fn) {
this.events[eventName] = this.events[eventName] || [];
this.events[eventName].push(fn);
},
unsubscribe: function (eventName, fn) {
if (this.events[eventName]) {
for (var i = 0; i < this.events[eventName].length; i++) {
if (this.events[eventName][i] === fn) {
this.events[eventName].splice(i, 1);
break;
}
};
}
},
publish: function (eventName, data) {
if (this.events[eventName]) {
this.events[eventName].forEach(function (fn) {
fn(data);
});
}
}
}
Usage
function test(){
events.subscribe("event1", function(data){
console.log("subscriber1 subscribe to event1 -> " + data);
});
events.subscribe("event1", function(data){
console.log("subscriber2 subscribe to event1 -> " + data);
});
events.subscribe("event1", function(data){
console.log("subscriber3 subscribe to event1 -> " + data);
});
events.subscribe("event1", function(data){
console.log("subscriber4 subscribe to event1 -> " + data);
});
// publish some data to all subscribers whose were registered to event1
events.publish("event1", "some data");
}
test();
Output
subscriber1 subscribe to event1 -> some data
subscriber2 subscribe to event1 -> some data
subscriber3 subscribe to event1 -> some data
subscriber4 subscribe to event1 -> some data
Using JavaScript class Keyword (after es2015)
class Event{
constructor(){
this.events = {};
}
subscribe(eventName, fn) {
this.events[eventName] = this.events[eventName] || [];
this.events[eventName].push(fn);
}
unsubscribe(eventName, fn) {
if (this.events[eventName]) {
for (var i = 0; i < this.events[eventName].length; i++) {
if (this.events[eventName][i] === fn) {
this.events[eventName].splice(i, 1);
break;
}
};
}
}
publish(eventName, data) {
if (this.events[eventName]) {
this.events[eventName].forEach(function(fn) {
fn(data);
});
}
}
}
function test1(){
var event = new Event();
event.subscribe("event1", function(data){
console.log("subscriber1 subscribe to event1 -> " + data);
});
event.subscribe("event1", function(data){
console.log("subscriber2 subscribe to event1 -> " + data);
});
event.subscribe("event1", function(data){
console.log("subscriber3 subscribe to event1 -> " + data);
});
event.subscribe("event1", function(data){
console.log("subscriber4 subscribe to event1 -> " + data);
});
// publish some data to all subscribers whose were registered to event1
event.publish("event1", "some data");
}
test1();
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