Question

I’ve got computed function which should basically listen to any changes in observable array (Items). The problem is that Knockout calls this function on initialisation. I know it does it to figure out its dependencies but in my case it’s a problem as it makes ajax request. Is it any solution beside introducing some counter variable to skip calling ajax on the first call?
Thanks.

function MyViewModel(data) {
    var self = this;
    self.nameToAdd = ko.observable("");
    self.Items = ko.observableArray(data.items || []);

    self.add = function () {
        self.Items.push({ Name: self.nameToAdd()});
        self.nameToAdd("");
    };

    self.remove = function (item) {
        self.Items.remove(item);
    };

    ko.computed(function () {
        $.ajax({
            url: "myUrl",
            type: 'POST',
            data: ko.toJSON(self.Items),
            contentType: 'application/json'
        });
    }, self);
}

Answer 1

I think what you really want is to manually subscribe to your Items array so when it is updated you call the ajax function.

self.Items.subscribe(function(){
    $.ajax({
        url: "myUrl",
        type: 'POST',
        data: ko.toJSON(self.Items),
        contentType: 'application/json'
    });
});

The function passed will only be called when a change has occured to the array itself, thus, not being called on initialization. See fiddle for example.