cesium/Source/Widgets/subscribeAndEvaluate.js

Cesium is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.

/*global define*/
define([
        '../ThirdParty/knockout'
    ], function(
        knockout) {
    'use strict';

    /**
     * Subscribe to a Knockout observable ES5 property, and immediately fire
     * the callback with the current value of the property.
     *
     * @private
     *
     * @exports subscribeAndEvaluate
     *
     * @param {Object} owner The object containing the observable property.
     * @param {String} observablePropertyName The name of the observable property.
     * @param {Function} callback The callback function.
     * @param {Object} [target] The value of this in the callback function.
     * @param {String} [event='change'] The name of the event to receive notification for.
     * @returns The subscription object from Knockout which can be used to dispose the subscription later.
     */
    function subscribeAndEvaluate(owner, observablePropertyName, callback, target, event) {
        callback.call(target, owner[observablePropertyName]);
        return knockout.getObservable(owner, observablePropertyName).subscribe(callback, target, event);
    }

    return subscribeAndEvaluate;
});