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HTML

<script src="http://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
How do I call the component view model foo function outside of the context of the foo element/template?
<br />
<br />

<foo></foo>

<template id="component-foo">Foo component</template>

JavaScript

ko.components.register("foo", {
    viewModel: FooComponentViewModel,
    template: {
        element: "component-foo"
    }
});

function FooComponentViewModel(params) {
    this.Foo = function () {
        alert("bar");
    };
}

var ViewModel = function () {
    // empty
};

var vm = ViewModel();
ko.applyBindings();