Magento – How to access other UI components

old post but this might help someone.

You just need to define a global variable before extending your component and assign the component context in initialize.

Then you can you self in your function.

define(['jquery','ko', 'uiComponent'], function ($, ko, Component) {
    ...
    var self;
    ...
    return Component.extend({
        initialize : function() {
         self = this;
    ...

        jumpToPage : function(item, event) {
          self. subscribeToQuery();
            console.log(this);
        }

The values of the exports object have to resolve to a name and a property of a UiComponent instance, separated by a ':', for example checkout.cart.total:title.
The export target name has to include the UI component "namespace".

In your example, you set the value to a string, which resolves to a property of the UiComponent that is the export source. The export is undefined when you inspect it because that is not a valid export target.

Here is an example that works:

defaults: {
    exportTarget: "foo.bar",
    exportTargetProperty: "showMessage",

    tracks: {
        shouldShowMessage: true
    },

    exports: {
        shouldShowMessage: '${$.exportTarget}:${$.exportTargetProperty}'
    }
}
...

The above will copy the value of the shouldShowMessage property into the property showMessage of a UiComponent with the full name foo.bar every time the value changes.
Note that this will not automatically make the target property a KO observable, too. That has to be declared explicitly, if value changes should trigger KO to rerender DOM nodes that access that property.

By the way, adding shouldShowMessage to the tracks object will make it a ko-es5 observable automagically. Using a literal ko.observable() works, too.

In the example above, the exportTarget and exportTargetProperty are configured in the defaults. They also could be specified as part of the UiComponent options in the JSON, which usually makes more sense, since that is where the UiComponent hierarchy including the UiComponent names are defined.

Finally, I would like to note that I personally think your solution using a value object to pass the value to the other UI component is better than using exports or imports. In my experience keeping shared state in the DOM or in UiComponents is a recipe for spaghetti OOP in all but the simplest cases.