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describe('Dependent Observable DOM', function() {
beforeEach(jasmine.prepareTestNode);
it('Should register DOM node disposal callback only if active after the initial evaluation', function() {
// Set up an active one
var nodeForActive = document.createElement('DIV'),
observable = ko.observable('initial'),
activeDependentObservable = ko.dependentObservable({ read: function() { return observable(); }, disposeWhenNodeIsRemoved: nodeForActive });
var nodeForInactive = document.createElement('DIV')
inactiveDependentObservable = ko.dependentObservable({ read: function() { return 123; }, disposeWhenNodeIsRemoved: nodeForInactive });
expect(activeDependentObservable.isActive()).toEqual(true);
expect(inactiveDependentObservable.isActive()).toEqual(false);
// Infer existence of disposal callbacks from presence/absence of DOM data. This is really just an implementation detail,
// and so it's unusual to rely on it in a spec. However, the presence/absence of the callback isn't exposed in any other way,
// and if the implementation ever changes, this spec should automatically fail because we're checking for both the positive
// and negative cases.
expect(ko.utils.domData.clear(nodeForActive)).toEqual(true); // There was a callback
expect(ko.utils.domData.clear(nodeForInactive)).toEqual(false); // There was no callback
});
it('Should dispose when DOM node is removed from the document and computed is re-evaluated', function() {
// Create node and add it to the document
var node = document.createElement('DIV');
testNode.appendChild(node);
// Create a computed that is disposed when the node is removed
var observable = ko.observable('initial'),
computed = ko.computed({
read: function() { return observable(); },
disposeWhenNodeIsRemoved: node
});
// Update computed and check that it's still active
observable('second');
expect(computed.isActive()).toEqual(true);
// Remove the node, update the computed, and check that it was disposed
testNode.removeChild(node);
observable('third');
expect(computed.isActive()).toEqual(false);
});
it('Should dispose when DOM node is removed from the document, but not before it\'s added', function() {
var node = document.createElement('DIV'),
observable = ko.observable('initial'),
computed = ko.computed({
read: function() { return observable(); },
disposeWhenNodeIsRemoved: node
});
// Update computed and check that it's still active
observable('second');
expect(computed.isActive()).toEqual(true);
// Add the node, update the computed, and check that it is still active
testNode.appendChild(node);
observable('third');
expect(computed.isActive()).toEqual(true);
// Remove the node, update the computed, and check that it was disposed
testNode.removeChild(node);
observable('fourth');
expect(computed.isActive()).toEqual(false);
});
})
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