Have you ever got into the situation of searching for an element in a large list while doing a loop over another collection?

This article will discuss how to find an element in a list of objects and especially how to improve the search in larger lists. Let’s start.

Filter

One of the first methods we can think of for finding elements in a list is filter.

The filter method creates a new array with all elements that pass the test performed by the predicate function.

A predicate is a function that takes an element and returns a boolean (true or…

This article looks at how to create a simple digital clock with React Hooks. In the process of building the Clock component displaying the current time, we are going to discuss the role of the useState and useEffect hooks in this case.

In this article, we will look at how the extend the standard array and discuss what we need to do to make it immutable.

Extending the Array

Let’s start by extending the Array class and adding a simple new method.

The extends keyword in class declarations creates a class that is a child of another one. In the next example, we are extending the default Array class.

The first method returns the first element from the array.

Behind the scene, the ExtendedArray.prototype object is created and it contains the new method and inherits from the Array.prototype object.

The Array.of method creates a…

This article describes how to write a simple algorithm rotating a string. It also deals with the case of special characters taking two code units.

To understand how to compute the new string, check a few examples.

• Rotating the string ABCDE to the left by 1 character results in BCDEA
• Trying to rotate the same text by 2 characters results in CDEAB.

It is important to note what happens when trying to rotate with a number of characters greater than the string size. For example, rotating by 6 characters result in BCDEA, and rotating by 7 characters gives CDEAB

Rotating to Left

Now…

There are cases when we work with an array of objects and want to create a new one containing objects with fewer properties. This article first looks at how to accomplish this for a specific case and then generalizes the solution.

Consider the following array of objects. Each episode has four properties and we want to extract only the id and the name.

const episodes = [{
    id: 1,
    title: "The One Where Ross Finds Out",
    season: 2,
    episode: 7
  },
  {
    id…

Functions stored on objects are called methods. This article looks at how to invoke such methods in a dynamic way.

The Bracket Notation

Objects allow accessing properties in a dynamic way using the bracket notation and providing an expression that is computed and used as the property name.

Here is an example of accessing a numeric property using the bracket notation.

const obj = {
  value: 1
}const propName = 'value';
console.log(obj[propName]);
//1

We can access any kind of property using the bracket notations even functions. Once we have access to a function property we can invoke it.

const obj = {…

In this article, first, we will look at how to achieve encapsulation using the module pattern, then with the modules available in the language, and last with factory functions which are actually based on the module pattern.

Module Pattern

In the beginning when modules were not part of the JavaScript languages, “modules” were implemented using the module pattern. It was the primary way to achieve encapsulation.

Encapsulation means hiding data and behavior.

The main idea was to hide the state. We cannot really say we are dealing with the module pattern if we are not hiding the state.

Here is an example…

Some objects look like arrays but they aren’t such.

An array-like object has a length property and index-like properties.

Here is an example.

const obj = {
  0: 'A',
  1: 'B',
  2: 'C',
  length : 3
}

Numeric keys are converted to strings so the previous object can be very well written using the string representation of the numbers. We get practically the same object.

const obj = {
  '0': 'A',
  '1': 'B',
  '2': 'C',
  length : 3
}

We are able to use the for statement on such an object.

for(let i = 0; i < obj.length; i++){…