knockout.js subscribe is not getting called on the first set

Question

I have a simple model class with observables. I simply want to subscribe to its sets. Here is the code that I have:

var dto = function (data) {

    var self = this;

    self.Value1 = ko.observable(data.Value1);

    self.Value1.subscribe(function(){

         console.log('here');

    });   

};

the console.log doesn't get called when the Value1 is first set (i.e. ko.observable(data.Value1)

How do I set it up that subsribe function happens on both initial and when it changes.

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Answer 1

There is no real support for triggering the subscribe function for the initial values.

What you can do is to call the valueHasMutated function after your subscribe:

self.Value1.subscribe(function(){
     console.log('here');
}); 
self.Value1.valueHasMutated();

Or you can just set your initial values after you've subscribed:

var dto = function (data) {
    var self = this;
    self.Value1 = ko.observable(); // only declare but not assign
    self.Value1.subscribe(function(){
         console.log('here');
    });   
    self.Value1(data.Value1); // assign initial value
};

knockout.js subscribe is not getting called on the first set

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