Question

Is there a clean way to bind only the initial value of an observable to a dom element using KnockoutJS?

I know you can achieve this by binding to a non-observable, but I’d rather not create a superfluous property just to hold the initial value of another observable property.

I tried this, but to no avail—the attribute is still updated with every change

<input type="text" id="tbName" 
  data-bind="value:name, attr: { 'data-initialnamevalue': ko.utils.unwrapObservable($data.name()) }" />

Answer 1

While I agree with Zero21xxx above, I guess you could use a custom binding where you provide an init method, but no update method.

Not sure it’s worth the effort versus just adding another property.

Here’s a simple example of what I mean: http://jsfiddle.net/ZkFRu/3/

The first paragraph binds the current value of a property, the second binds the initial value. Clicking the button increments the property.