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// The Emitter class provides the ability to call `.on()` on Dropzone to listen |
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// to events. |
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// It is strongly based on component's emitter class, and I removed the |
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// functionality because of the dependency hell with different frameworks. |
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export default class Emitter { |
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// Add an event listener for given event |
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on(event, fn) { |
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this._callbacks = this._callbacks || {}; |
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// Create namespace for this event |
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if (!this._callbacks[event]) { |
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this._callbacks[event] = []; |
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} |
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this._callbacks[event].push(fn); |
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return this; |
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} |
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|
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emit(event, ...args) { |
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this._callbacks = this._callbacks || {}; |
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let callbacks = this._callbacks[event]; |
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|
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if (callbacks) { |
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for (let callback of callbacks) { |
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callback.apply(this, args); |
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} |
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} |
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// trigger a corresponding DOM event |
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if (this.element) { |
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this.element.dispatchEvent( |
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this.makeEvent("dropzone:" + event, { args: args }) |
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); |
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} |
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return this; |
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} |
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|
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makeEvent(eventName, detail) { |
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let params = { bubbles: true, cancelable: true, detail: detail }; |
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|
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if (typeof window.CustomEvent === "function") { |
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return new CustomEvent(eventName, params); |
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} else { |
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// IE 11 support |
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// https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent/CustomEvent |
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var evt = document.createEvent("CustomEvent"); |
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evt.initCustomEvent( |
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eventName, |
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params.bubbles, |
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params.cancelable, |
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params.detail |
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); |
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return evt; |
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} |
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} |
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|
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// Remove event listener for given event. If fn is not provided, all event |
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// listeners for that event will be removed. If neither is provided, all |
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// event listeners will be removed. |
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off(event, fn) { |
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if (!this._callbacks || arguments.length === 0) { |
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this._callbacks = {}; |
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return this; |
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} |
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|
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// specific event |
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let callbacks = this._callbacks[event]; |
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if (!callbacks) { |
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return this; |
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} |
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|
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// remove all handlers |
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if (arguments.length === 1) { |
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delete this._callbacks[event]; |
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return this; |
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} |
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|
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// remove specific handler |
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for (let i = 0; i < callbacks.length; i++) { |
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let callback = callbacks[i]; |
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if (callback === fn) { |
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callbacks.splice(i, 1); |
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break; |
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} |
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} |
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|
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return this; |
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} |
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} |
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|
