Check if object exist in array before push

I have an empty array and a selectable tree, and every time when the user is checking or un-checking a node I'm pushing the node's id and if the checkbox is true or false.

But right now if the user will check and then un-check a node there will be two objects in the array of the same node how can i make sure that doesn't happen?

//creating empty array

var checkedItems = []; 

//(in kendo observable) on user selection I'm pushing the checked node to array

onItemChecked : function (e) {
    var node = e.sender.dataItem(e.node);
    checkedItems.push({Id: node.Id, IsChecked: node.checked});
},