Question

34

knockout.js input box event change - passes old value

rated 0 times [ 38] [ 4] / answers: 1 / hits: 75112 / 12 Years ago, sat, march 3, 2012, 12:00:00

When adding a change event binding to an input box using knockout.js the old value is passed to the change function when the event is fired. I can work around this by using blur. Is this the intended behavior? Is the idea to use the change event to have the old value and then use a normal selector to get the value from the dom? It seems counter intuitive.

jsFiddle Example

JavaScript

----------

var data = {

    saved_value:1,

    value_changed: function(data){

        alert(data.saved_value());

    }

};

var viewModel = ko.mapping.fromJS(data);

ko.applyBindings(viewModel);



HTML

----

Current Value:<span data-bind=text:saved_value></span><br/>

<input data-bind=event:{change:value_changed},value:saved_value></input>

Answers

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jennie

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2 Years ago

answered 13 Years ago turnerf · Accepted Answer

Try using the text and value bindings:

Current Value:<span data-bind=text: saved_value></span><br/>

<input data-bind=value: saved_value></input>

And change the JavaScript to this:

var data = {

    saved_value: 1    

};



var viewModel = ko.mapping.fromJS(data);

ko.applyBindings(viewModel);

Here's an associated jsFiddle: http://jsfiddle.net/6zmJs/

If you want to alert() the value of saved_value when it is updated you could use ko.computed or viewModel.saved_value.subscribe(function(value) { alert(value); }); -- although those aren't the only ways to do this.