The ultimate guide to coding interviews: Learn and practice JavaScript design patterns tested by FAANG engineers. Get interview-ready in just a few hours with battle-tested solutions.

If you're an experienced developer, chances are your interviewer won't ask you about language syntax. Instead, they'll focus on things that test your understanding of software architecture, and how capable you are at finding optimized solutions to given problems. 

That’s where a strong understanding of design patterns comes in handy. It's often useful to be able to draw on established patterns instead of reinventing the wheel.

In this course, you will learn how to effectively deploy design patterns to answer interview questions. The course is divided into four sections: Creational Patterns, Structural Patterns, Behavioral Patterns, and Architectural Patterns. Each section has its own set of design patterns which you’ll learn to use through various challenges. 

Every challenge contains a detailed solution explanation. By the end of this course (and with some practice), you will be able to confidently use design patterns to tackle advanced coding interview questions in JavaScript.

JavaScript Design Patterns for Coding Interviews

## Problem statement

In this challenge, you need to use the MVVM pattern to change the color of the "color" you write in the input field. 

In the `Model`, you need to define the following functions: 

* `subscribe`: Registers an observer

* `notifyObservers`: Notifies the observer of a change

* `getCurrentColor`: Returns the current color

* `setColor`: Sets a new color


In the `ViewModel`, you need to define the `bind` function, which reflects changes made in the view on the model and vice versa. It should do the following as well:

* If you write `green` in the input, the color of the text `green` should change to `red`

* If you write `red` in the input, the color of the text `red` should change to `blue`

* If you write `blue` in the input, the color of the text `blue` should change to `green`

The view is provided to you in the form of the HTML code. Study it carefully before writing the JavaScript code.

## Input

 The name of the color


## Output

The color of the text changes to green, red, or blue according to the rules given

## Sample input
```
green
red
blue 
```

## Sample output


green

red

blue

# Problem statement

In this challenge, you need to use the MVVM pattern to change the color of the "color" you write in the input field. 

In the `Model`, you need to define the following functions: 

* `subscribe`: Registers an observer

* `notifyObservers`: Notifies the observer of a change

* `getCurrentColor`: Returns the current color

* `setColor`: Sets a new color


In the `ViewModel`, you need to define the `bind` function, which reflects changes made in the view on the model and vice versa. It should do the following as well:

* If you write `green` in the input, the color of the text `green` should change to `red`

* If you write `red` in the input, the color of the text `red` should change to `blue`

* If you write `blue` in the input, the color of the text `blue` should change to `green`

The view is provided to you in the form of the HTML code. Study it carefully before writing the JavaScript code.

# Input

 The name of the color


# Output

The color of the text changes to green, red, or blue according to the rules given

# Sample input
```
green
red
blue 
```

# Sample output


green

red

blue

# Problem statement

In this challenge, you need to use the MVVM pattern to change the color of the "color" you write in the input field. 

In the `Model`, you need to define the following functions: 

* `subscribe`: Registers an observer

* `notifyObservers`: Notifies the observer of a change

* `getCurrentColor`: Returns the current color

* `setColor`: Sets a new color


In the `ViewModel`, you need to define the `bind` function, which reflects changes made in the view on the model and vice versa. It should do the following as well:

* If you write `green` in the input, the color of the text `green` should change to `red`

* If you write `red` in the input, the color of the text `red` should change to `blue`

* If you write `blue` in the input, the color of the text `blue` should change to `green`

The view is provided to you in the form of the HTML code. Study it carefully before writing the JavaScript code.

# Input

 The name of the color


# Output

The color of the text changes to green, red, or blue according to the rules given

# Sample input
```
green
red
blue 
```

# Sample output


green

red

blue

In this challenge, you have to implement the MVVM pattern to solve the given problem.

Before We Begin

Introduction To Design Patterns

Creational Patterns

Structural Patterns

Behavioral Patterns

Architectural Patterns

Conclusion

Challenge: MVVM Pattern

Problem statement