How to subscribe to observable in the parent model from a component in knockout.js?

@shyann 

In knockout.js, you can subscribe to an observable in the parent model from a component by passing the parent model as a parameter to the component and then accessing the parent model's observable from within the component.

Here's an example:

1. Define your parent model with an observable property:

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function ParentModel() {
    this.parentObservable = ko.observable('Initial value');
}

1. Create your component and pass the parent model as a parameter:

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ko.components.register('my-component', {
    viewModel: function(params) {
        this.parentModel = params.parentModel;

        this.subscribeToParentObservable = function() {
            this.parentModel.parentObservable.subscribe(function(newValue) {
                console.log('Parent observable changed to: ' + newValue);
            });
        };
    },
    template: '<button data-bind="click: subscribeToParentObservable">Subscribe to parent observable</button>'
});

1. Include the component in your HTML and pass the parent model as a parameter:

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<div data-bind="component: { name: 'my-component', params: { parentModel: $root } }"></div>

In this example, the component subscribes to the parent model's parentObservable property and logs a message whenever the value of the observable changes. You can further extend this example to perform any actions based on the changes in the parent model's observable.