观察者模式

观察者模式_第1张图片
观察者模式

let Event = (function() {

let global = this,

Event,

_default = 'default';

Event = function() {

let _listen,

_trigger,

_remove,

_slice = Array.prototype.slice,

_shift = Array.prototype.shift,

_unshift = Array.prototype.unshift,

namespaceCache = {},

_create,

find,

each = function(ary, fn) {

let ret;

for (let i = 0, l = ary.length; i < l; i++) {

let 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 (let i = cache[key].length; i >= 0; i--) {

if (cache[key][i] === fn) {

cache[key].splice(i, 1);

}

}

} else {

cache[key] = [];

}

}

};

_trigger = function() {

let 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 thisl.apply(_self, args);

})

};

_create = function(namespace) {

var namespace = namespace || _default,

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() {

let 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) {

let event = this.create();

event.one(key, fn, last);

},

remove: function(key, fn) {

let event = this.create();

event.remove(key, fn);

},

listen: function(key, fn, last) {

let event = this.create();

event.listen(key, fn, last);

},

trigger: function() {

let event = this.create();

event.trigger.apply(this, arguments);

}

};

}();

return Event;

})();

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