---
title: "What are subscriptions in Knockout.js?"
description: "What are subscriptions in Knockout.js?"
author: "Ashutosh Patel"
published: 2024-06-28
updated: 2024-06-28
canonical: https://www.mindstick.com/interview/33931/what-are-subscriptions-in-knockout-js
category: "knockcout js"
tags: ["javascript", "knockout.js"]
reading_time: 3 minutes
---
# What are subscriptions in Knockout.js?
#### Knockout.js Subscribe() method
In Knockout.js, a subscription refers to a mechanism that allows you to track observable changes (which allows you to track changes to properties). Subscriptions enable you to respond to changes in observables by executing custom logic each time the value of an observable changes.
Here is how subscriptions work in Knockout.js,
## Creating a Subscription
You can create a subscription for an observable by calling a `subscribe` method on the observable. The `subscribe` method takes a callback function as an argument. This callback function will be called whenever the value of the observable changes
```javascript
var myObservable = ko.observable('initial value');
myObservable.subscribe(function(newValue) {
myObservable("New value is: "+ newValue)
});
```
## Automatic Execution
When you use that function to create a new value of an observable (e.g., `myObservable(newValue)`), Knockout.js automatically notifies all clients by calling their callback function
## Example-
```html
subscribe method Example
Knockout.js subscribe() Example
Current value:
```
## Output-
**Also, Read:** [Explain Inline vs. External Templates in knockout.js.](https://www.mindstick.com/forum/160794/explain-inline-vs-external-templates-in-knockout-js)
## Answers
### Answer by Ashutosh Patel
#### Knockout.js Subscribe() method
In Knockout.js, a subscription refers to a mechanism that allows you to track observable changes (which allows you to track changes to properties). Subscriptions enable you to respond to changes in observables by executing custom logic each time the value of an observable changes.
Here is how subscriptions work in Knockout.js,
## Creating a Subscription
You can create a subscription for an observable by calling a `subscribe` method on the observable. The `subscribe` method takes a callback function as an argument. This callback function will be called whenever the value of the observable changes
```javascript
var myObservable = ko.observable('initial value');
myObservable.subscribe(function(newValue) {
myObservable("New value is: "+ newValue)
});
```
## Automatic Execution
When you use that function to create a new value of an observable (e.g., `myObservable(newValue)`), Knockout.js automatically notifies all clients by calling their callback function
## Example-
```html
subscribe method Example