knockout.js – Page 5

Bind to simple array of strings

February 21, 2023 by Tarik

From the documentation, the answer is: When using a template: ${$data} When not using a template: $data

Knockout.js v2.3.0 error “You cannot apply bindings multiple times to the same element”

February 11, 2023 by Tarik

You need to remove the bindings before you use applyBindings again: ko.cleanNode($element[0]);

Setting the id attribute with knockoutjs including a prefix

February 8, 2023 by Tarik

Actually used this today – to unwrap the observable I had to do: <button data-bind=”attr: { id: ‘prefix_’ + $index() }”> Send </button> Hope this helps.

Force a computed property function to run

February 2, 2023 by Tarik

I realized my first answer missed your point, and won’t solve your issue. The problem is that a computed will only reevaluate if there is some observable that forces it to re-evaluate. There is no native way to force a computed to re-evaluate. However, you can get around this with some hackery by creating a … Read more

Get previous value of an observable in subscribe of same observable

January 27, 2023 by Tarik

ko.subscribable.fn.subscribeChanged = function (callback) { var oldValue; this.subscribe(function (_oldValue) { oldValue = _oldValue; }, this, ‘beforeChange’); this.subscribe(function (newValue) { callback(newValue, oldValue); }); }; Use the above like this: MyViewModel.MyObservableProperty.subscribeChanged(function (newValue, oldValue) { });

Change event on select with knockout binding, how can I know if it is a real change?

January 15, 2023 by Tarik

Actually you want to find whether the event is triggered by user or program , and its obvious that event will trigger while initialization. The knockout approach of adding subscription won’t help in all cases, why because in most of the model will be implemented like this init the model with undefined data , just … Read more

How to conditionally push an item in an observable array?

January 4, 2023 by Tarik

An observableArray exposes an indexOf function (wrapper to ko.utils.arrayIndexOf). This allows you to do: if (myObservableArray.indexOf(itemToAdd) < 0) { myObservableArray.push(itemToAdd); } If the two are not actually a reference to the same object and you want to run custom comparison logic, then you can use ko.utils.arrayFirst like: var match = ko.utils.arrayFirst(myObservableArray(), function(item) { return itemToAdd.id … Read more