How to create a computed observable array in Knockout

Question

I would like to know how to create a computed observable array.

In my view model, I have 2 observable arrays, and I would like to have a computed observable array

Answer 1

I'm not sure if this is the most efficient option - but it is fairly simple and works for me. The ko.computed returns an observable array as below:

self.computedArrayValue = ko.computed(function() {
    var all = ko.observableArray([]);
    ....
    return all(); 
});

A working example of the code: Html:

Javascript function on the view model:

self.days = ko.computed(function() {
    var all = ko.observableArray([]);
    var month = self.selectedMonth();   //observable
    var year = self.selectedYear();     //observable
    for (var i = 1; i < 29; i++) {
        all.push(i);
    }
    if (month == "Feb" && year % 4 == 0) {
        all.push(29);
    } else if (["Jan","Mar","May","Jul","Aug","Oct","Dec"].find((p) => p == month)) {
        [29,30,31].forEach((i) => all.push(i));
    } else if (month != "Feb") {
        [29,30].forEach((i) => all.push(i));                
    }
    return all(); 
});