张静宜对订阅-发布模式的理解

var Event = (function(){
var global = this,
Event,
_default = 'default';
Event = function(){
var _listen,
_trigger,
_remove,
_slice = Array.prototype.slice,
_shift = Array.prototype.shift,
_unshift = Array.prototype.unshift,
namespaceCache = {},
_create,
find,
each = function( ary, fn ){
var ret;
for ( var i = 0, l = ary.length; i < l; i++ ){
var n = ary[i];
ret = fn.call( n, i, n);
}
return ret;
};
_listen = function( key, fn, cache ){
if ( !cache[ key ] ){
cache[ key ] = [];
}
cache[key].push( fn );
};
_remove = function( key, cache ,fn){
if ( cache[ key ] ){
if( fn ){
for( var i = cache[ key ].length; i >= 0; i-- ){
if( cache[ key ][i] === fn ){
cache[ key ].splice( i, 1 );
}
}
}else{
cache[ key ] = [];
}
}
};
_trigger = function(){
var cache = _shift.call(arguments),
key = _shift.call(arguments),
args = arguments,
_self = this,
ret,
stack = cache[ key ];
if ( !stack || !stack.length ){
return;
}
return each( stack, function(){
return this.apply( _self, args );
});
};
_create = function( namespace ){
var namespace = namespace || _default;
var cache = {},
offlineStack = [], // 离线事件
ret = {
listen: function( key, fn, last ){
_listen( key, fn, cache );
if ( offlineStack === null ){
return;
}
if ( last === 'last' ){
offlineStack.length && offlineStack.pop()();
}else{
each( offlineStack, function(){
this();
});
}
offlineStack = null;
},
one: function( key, fn, last ){
_remove( key, cache );
this.listen( key, fn ,last );
},
remove: function( key, fn ){
_remove( key, cache ,fn);
},
trigger: function(){
var fn,
args,
_self = this;
_unshift.call( arguments, cache );
args = arguments;
fn = function(){
return _trigger.apply( _self, args );
};
if ( offlineStack ){
return offlineStack.push( fn );
}
return fn();
}
};
return namespace ?
( namespaceCache[ namespace ] ? namespaceCache[ namespace ] :
namespaceCache[ namespace ] = ret )
: ret;
};
return {
create: _create,
one: function( key,fn, last ){
var event = this.create( );
event.one( key,fn,last );
},
remove: function( key,fn ){
var event = this.create( );
event.remove( key,fn );
},
listen: function( key, fn, last ){
var event = this.create( );
event.listen( key, fn, last );
},
trigger: function(){
var event = this.create( );
event.trigger.apply( this, arguments );
}
};
}();
return Event;
})();