定义
发布订阅模式理念和观察者模式相同，但是处理方式上不同：订阅者把自己想订阅的事件注册到调度中心，当该事件触发时候，发布者发布该事件到调度中心（顺带上下文），由调度中心统一调度订阅者注册到调度中心的处理代码。
双向解耦，发布者和订阅者都不用清楚对方，全部由订阅中心做处理。
实现
1 | var Event = (function () { |
ionic中的Events实现
1 | (function (factory) { |
* @demo /docs/demos/src/events/
*/
var Events = (function () {
function Events() {
this._channels = [];
}
/**
* Subscribe to an event topic. Events that get posted to that topic will trigger the provided handler.
*
* @param {string} topic the topic to subscribe to
* @param {function} handler the event handler
*/
Events.prototype.subscribe = function (topic) {
var _this = this;
var handlers = [];
for (var _i = 1; _i < arguments.length; _i++) {
handlers[_i - 1] = arguments[_i];
}
if (!this._channels[topic]) {
this._channels[topic] = [];
}
handlers.forEach(function (handler) {
_this._channels[topic].push(handler);
});
};
/**
* Unsubscribe from the given topic. Your handler will no longer receive events published to this topic.
*
* @param {string} topic the topic to unsubscribe from
* @param {function} handler the event handler
*
* @return true if a handler was removed
*/
Events.prototype.unsubscribe = function (topic, handler) {
if (handler === void 0) { handler = null; }
var t = this._channels[topic];
if (!t) {
// Wasn't found, wasn't removed
return false;
}
if (!handler) {
// Remove all handlers for this topic
delete this._channels[topic];
return true;
}
// We need to find and remove a specific handler
var i = t.indexOf(handler);
if (i < 0) {
// Wasn't found, wasn't removed
return false;
}
t.splice(i, 1);
// If the channel is empty now, remove it from the channel map
if (!t.length) {
delete this._channels[topic];
}
return true;
};
/**
* Publish an event to the given topic.
*
* @param {string} topic the topic to publish to
* @param {any} eventData the data to send as the event
*/
Events.prototype.publish = function (topic) {
var args = [];
for (var _i = 1; _i < arguments.length; _i++) {
args[_i - 1] = arguments[_i];
}
var t = this._channels[topic];
if (!t) {
return null;
}
var responses = [];
t.forEach(function (handler) {
responses.push(handler.apply(void 0, args));
});
return responses;
};
return Events;
}());
exports.Events = Events;
/**
* @hidden
*/
function setupEvents(plt, dom) {
var events = new Events();
var win = plt.win();
var doc = plt.doc();
// start listening for resizes XXms after the app starts
plt.timeout(function () {
win.addEventListener('online', function (ev) {
events.publish('app:online', ev);
}, false);
win.addEventListener('offline', function (ev) {
events.publish('app:offline', ev);
}, false);
win.addEventListener('orientationchange', function (ev) {
events.publish('app:rotated', ev);
});
// When that status taps, we respond
win.addEventListener('statusTap', function () {
// TODO: Make this more better
var el = doc.elementFromPoint(plt.width() / 2, plt.height() / 2);
if (!el) {
return;
}
var contentEle = el.closest('.scroll-content');
if (contentEle) {
var style = contentEle.style;
var scroll = new scroll_view_1.ScrollView(null, plt, dom);
scroll._el = contentEle;
// We need to stop scrolling if it's happening and scroll up
style['WebkitBackfaceVisibility'] = 'hidden';
style['WebkitTransform'] = 'translate3d(0,0,0)';
dom.write(function () {
style.overflow = 'hidden';
function finish() {
style.overflow = '';
style['WebkitBackfaceVisibility'] = '';
style['WebkitTransform'] = '';
}
var didScrollTimeout = plt.timeout(function () {
finish();
}, 400);
scroll.scrollTo(0, 0, 300).then(function () {
plt.cancelTimeout(didScrollTimeout);
finish();
});
});
}
});
}, 2000);
return events;
}
exports.setupEvents = setupEvents;
/**
* @hidden
*/
function setupProvideEvents(plt, dom) {
return function () {
return setupEvents(plt, dom);
};
}
exports.setupProvideEvents = setupProvideEvents;
});1
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去除一些不太重要的东西
```javascript
var Events = (function () {
function Events() {
this._channels = [];
}
/**
* Subscribe to an event topic. Events that get posted to that topic will trigger the provided handler.
*
* @param {string} topic the topic to subscribe to
* @param {function} handler the event handler
*/
Events.prototype.subscribe = function (topic) {
var _this = this;
var handlers = [];
for (var _i = 1; _i < arguments.length; _i++) {
handlers[_i - 1] = arguments[_i];
}
if (!this._channels[topic]) {
this._channels[topic] = [];
}
handlers.forEach(function (handler) {
_this._channels[topic].push(handler);
});
};
/**
* Unsubscribe from the given topic. Your handler will no longer receive events published to this topic.
*
* @param {string} topic the topic to unsubscribe from
* @param {function} handler the event handler
*
* @return true if a handler was removed
*/
Events.prototype.unsubscribe = function (topic, handler) {
if (handler === void 0) {
handler = null;
}
var t = this._channels[topic];
if (!t) {
// Wasn't found, wasn't removed
return false;
}
if (!handler) {
// Remove all handlers for this topic
delete this._channels[topic];
return true;
}
// We need to find and remove a specific handler
var i = t.indexOf(handler);
if (i < 0) {
// Wasn't found, wasn't removed
return false;
}
t.splice(i, 1);
// If the channel is empty now, remove it from the channel map
if (!t.length) {
delete this._channels[topic];
}
return true;
};
/**
* Publish an event to the given topic.
*
* @param {string} topic the topic to publish to
* @param {any} eventData the data to send as the event
*/
Events.prototype.publish = function (topic) {
var args = [];
for (var _i = 1; _i < arguments.length; _i++) {
args[_i - 1] = arguments[_i];
}
var t = this._channels[topic];
if (!t) {
return null;
}
var responses = [];
t.forEach(function (handler) {
responses.push(handler.apply(void 0, args));
});
return responses;
};
return Events;
}());