mirror of
https://gerrit.wikimedia.org/r/mediawiki/extensions/Popups
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39 lines
1.1 KiB
JavaScript
39 lines
1.1 KiB
JavaScript
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/**
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* @typedef {Function} ext.popups.ChangeListener
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* @param {Object} prevState The previous state
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* @param {Object} state The current state
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*/
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/**
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* Registers a change listener, which is bound to the
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* [store](http://redux.js.org/docs/api/Store.html).
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*
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* A change listener is a function that is only invoked when the state in the
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* [store](http://redux.js.org/docs/api/Store.html) changes. N.B. that there
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* may not be a 1:1 correspondence with actions being dispatched to the store
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* and the state in the store changing.
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*
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* See [Store#subscribe](http://redux.js.org/docs/api/Store.html#subscribe)
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* for more information about what change listeners may and may not do.
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*
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* @param {Redux.Store} store
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* @param {ext.popups.ChangeListener} callback
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*/
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module.exports = function ( store, callback ) {
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// This function is based on the example in [the documentation for
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// Store#subscribe](http://redux.js.org/docs/api/Store.html#subscribe),
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// which was written by Dan Abramov.
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var state;
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store.subscribe( function () {
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var prevState = state;
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state = store.getState();
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if ( prevState !== state ) {
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callback( prevState, state );
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}
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} );
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};
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