With getInstance() you can also create the component if it does not exists. From $SPLUNK_HOME/share/splunk/search_mrsparkle/exposed/js/splunkjs/mvc/registry.js:
/**
 * @param id                The id of the instance to return.
 * @param options           (Optional).
 * @param options.create    Whether to create a new token model with
 *                          the given name if the specified instance
 *                          does not exist.
 * @return                  The specified instance, or a falsy value
 *                          if the instance does not exist and
 *                          options.create is omitted or false.
 */
getInstance: function(id, options) {
    options = options || {};
    // If an instance with this id doesn't exist,
    // figure out whether we want to create one or not.
    if (!this.has(id)) {
        if (options.create) {
            this.registerInstance(id, this._createTokenModel(id));
        }
        else {
            console.error(this.createError("No instance with id: " + id));
        }
    }
    return this.get(id);
},
With getInstance() you can also create the component if it does not exists. From $SPLUNK_HOME/share/splunk/search_mrsparkle/exposed/js/splunkjs/mvc/registry.js:
/**
 * @param id                The id of the instance to return.
 * @param options           (Optional).
 * @param options.create    Whether to create a new token model with
 *                          the given name if the specified instance
 *                          does not exist.
 * @return                  The specified instance, or a falsy value
 *                          if the instance does not exist and
 *                          options.create is omitted or false.
 */
getInstance: function(id, options) {
    options = options || {};
    // If an instance with this id doesn't exist,
    // figure out whether we want to create one or not.
    if (!this.has(id)) {
        if (options.create) {
            this.registerInstance(id, this._createTokenModel(id));
        }
        else {
            console.error(this.createError("No instance with id: " + id));
        }
    }
    return this.get(id);
},
