---
title: "Explain the role of observables and observables arrays in Knockout.js"
description: "Explain the role of observables and observables arrays in Knockout.js"
author: "Ashutosh Patel"
published: 2024-06-27
updated: 2024-06-27
canonical: https://www.mindstick.com/interview/33928/explain-the-role-of-observables-and-observables-arrays-in-knockout-js
category: "knockcout js"
tags: ["javascript", "knockout.js", "knockout observables"]
reading_time: 4 minutes
---
# Explain the role of observables and observables arrays in Knockout.js
#### Knockout.js Observables and Observables Array
sure! In Knockout.js, observables and observable arrays play an important role in keeping the two-way data binding between your JavaScript data model and your HTML UI elements dynamic and up-to-date
**Observables**\
Observables are special JavaScript objects provided by Knockout.js (ko.observable()). Your data values are bound and made visible, meaning that Knockout.js is able to monitor changes to these values and automatically update the UI whenever they change.
## Example-
```html
First Name:
Last Name:
Age:
```
\
Each time you update `this.firstName('Jane')` or `this.age(31)`, the corresponding elements in your HTML will automatically be updated.
Visible arrays:\
Observable arrays (ko.observableArray()) are special observables that manage an array of objects or values. They provide methods for making changes to the array (such as push, pop, splice, etc.), and ensure that any changes are tracked and propagated to the UI.
**Observable Arrays**\
This would reveal people’s names and ages. When you add or remove objects from `viewModel.people`, Knockout.js will update the DOM accordingly.
Example-
```html
Data Binding Example
Knockout.js data-bind Example
-
```
## output-
## Knockout.js Observable Array
- Alice - 28
- Bob - 35
- Carol - 32
Observables and Observable arrays are fundamental to Knockout.js for achieving reactive and dynamic web applications, making it easy to manage and synchronize data between JavaScript and HTML.
**Also, Read:** [Explain the role of observables and computed observables in Knockout.js?](https://www.mindstick.com/forum/160790/explain-the-role-of-observables-and-computed-observables-in-knockout-js)
## Answers
### Answer by Ashutosh Patel
#### Knockout.js Observables and Observables Array
sure! In Knockout.js, observables and observable arrays play an important role in keeping the two-way data binding between your JavaScript data model and your HTML UI elements dynamic and up-to-date
**Observables**\
Observables are special JavaScript objects provided by Knockout.js (ko.observable()). Your data values are bound and made visible, meaning that Knockout.js is able to monitor changes to these values and automatically update the UI whenever they change.
## Example-
```html
First Name:
Last Name:
Age:
```
\
Each time you update `this.firstName('Jane')` or `this.age(31)`, the corresponding elements in your HTML will automatically be updated.
Visible arrays:\
Observable arrays (ko.observableArray()) are special observables that manage an array of objects or values. They provide methods for making changes to the array (such as push, pop, splice, etc.), and ensure that any changes are tracked and propagated to the UI.
**Observable Arrays**\
This would reveal people’s names and ages. When you add or remove objects from `viewModel.people`, Knockout.js will update the DOM accordingly.
Example-
```html
Data Binding Example