What is evaluator function in knockout.js?

@daisha 

An evaluator function in Knockout.js is a function that calculates a value based on some observable or computed observable in the ViewModel. It is typically used in data bindings to display calculated values on the UI.

For example, an evaluator function could be used to calculate the total price of items in a shopping cart based on the quantity and price of each item. The evaluator function would be triggered whenever the quantity or price of an item changes, and the updated total price would be displayed on the UI.

Evaluator functions can be defined as plain JavaScript functions or as computed observables in Knockout.js, which automatically updates whenever its dependencies change. This allows for declarative data-binding without having to manually update the UI when the underlying data changes.