// event.jsclassEvent{ /** * style="color: #333333; font-weight: bold;">if (typeof fn != "function") { console.error('fn must be a function') return } this._cbs = this._cbs || {} ;(this._cbs[event] = this._cbs[event] || []).push(fn) } /** * emit 方法接受一個事件名稱參數(shù)，在 Event 對象的 _cbs 屬性中取出對應(yīng)的數(shù)組，并逐個執(zhí)行里面的回調(diào)函數(shù) */ emit (event) { this._cbs = this._cbs || {} var callbacks = this._cbs[event], args if (callbacks) { callbacks = callbacks.slice(0) args = [].slice.call(arguments, 1) for (var i = 0, len = callbacks.length; i < len; i++) { callbacks[i].apply(null, args) } } } /** * off 方法接受事件名稱和當初注冊的回調(diào)函數(shù)作參數(shù)，在 Event 對象的 _cbs 屬性中刪除對應(yīng)的回調(diào)函數(shù)。 */ off (event, fn) { this._cbs = this._cbs || {} // all if (!arguments.length) { this._cbs = {} return } var callbacks = this._cbs[event] if (!callbacks) return // remove all handlers if (arguments.length === 1) { delete this._cbs[event] return } // remove specific handler var cb for (var i = 0, len = callbacks.length; i < len; i++) { cb = callbacks[i] if (cb === fn || cb.fn === fn) { callbacks.splice(i, 1) break } } return

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