主要思想
通过逻辑处理函数/对象event，使事件订阅和发布过程忽略事件的具体处理过程
订阅时只需要给到event要订阅的事件A，和响应函数，
发布时给到event事件A被触发和相关参数，即可执行订阅时的响应函数
event 充当中介者的角色，管理事件响应的存储和执行
1.简单实现1
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30let event = {
caches:{},
on:function(name,fn){
if(!this.caches[name]){
this.caches[name] = []
}
this.caches[name].push(fn)
},
emit:function(name,...args){
if(!this.caches[name]){return}
for(let i=0;i<this.caches[name].length;i++){
let fn=this.caches[name][i]
fn(args)
}
},
remove:function(name,fn){
if(this.caches[name].length<1){return}
for(let i=0;i<this.caches[name].length;i++){
let fn1=this.caches[name][i]
if(fn === fn1){
this.caches[name].splice(i,1)
}
}
}
}
let fn1 = (val)=>{console.log(val,1)}
let fn2 = (val)=>{console.log(val,2)}
event.on('aaa',fn1)
event.on('aaa',fn2)
event.emit('aaa','fire!')
2.全局事件冲突1
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133var 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;
})();