41 lines
1008 B
JavaScript
41 lines
1008 B
JavaScript
function createBroadcast (initialState) {
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var listeners = {};
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var id = 1;
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var _state = initialState;
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function getState () {
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return _state
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}
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function setState (state) {
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_state = state;
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var keys = Object.keys(listeners);
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var i = 0;
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var len = keys.length;
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for (; i < len; i++) {
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// if a listener gets unsubscribed during setState we just skip it
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if (listeners[keys[i]]) { listeners[keys[i]](state); }
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}
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}
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// subscribe to changes and return the subscriptionId
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function subscribe (listener) {
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if (typeof listener !== 'function') {
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throw new Error('listener must be a function.')
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}
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var currentId = id;
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listeners[currentId] = listener;
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id += 1;
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return currentId
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}
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// remove subscription by removing the listener function
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function unsubscribe (id) {
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delete listeners[id];
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}
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return { getState: getState, setState: setState, subscribe: subscribe, unsubscribe: unsubscribe }
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}
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module.exports = createBroadcast;
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