Question

I have one ViewModel that contains two arrays: arr1 and arr2. I would like arr2 to contains exactly what the arr1 contains. How can I do that?

var myViewModel = function() {
    this.arr1 = ko.observableArray([]);
    this.arr2 = ko.observableArray(this.arr1); //Doesn't work - I need to bind arr2 to changes in arr1
}

Answer 1

If you want to store reference to array’s elements use should unwrap observable:

var myViewModel = function() {
    this.arr1 = ko.observableArray([]);
    this.arr2 = ko.observableArray(this.arr1());
}

If want clone array use Slice function of array:

var myViewModel = function() {
    this.arr1 = ko.observableArray([]);
    this.arr2 = ko.observableArray(this.arr1.slice(0)); 
}