Javascript Articles

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Is it possible to create a new data type in JavaScript?

Yaswanth Varma
Yaswanth Varma
Updated on 15-Mar-2026 3K+ Views

The task we are going to perform in this article is to explore whether it's possible to create a new data type in JavaScript. For instance, let's consider we have a variable student: var student = "username"; console.log(typeof student); string Now, I want to declare a custom type for that variable and print that in the output. Let's dive into the article to learn more about creating a new data type in JavaScript. Can You Create Custom Data Types? Yes, it is possible to create custom data types in JavaScript using ...

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How to count number of occurrences of repeated names in an array - JavaScript?

Yaswanth Varma
Yaswanth Varma
Updated on 15-Mar-2026 1K+ Views

In JavaScript, counting occurrences of repeated names in an array is a common task when working with data analysis and statistics. This involves iterating through an array of objects and tracking how many times each name appears. Let's consider an array consisting of student details with repeated names: var details = [ { studentName: "John", studentAge: 23 }, { studentName: "David", studentAge: 24 ...

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Make strings in array become keys in object in a new array in JavaScript?

Yaswanth Varma
Yaswanth Varma
Updated on 15-Mar-2026 2K+ Views

The task we are going to perform in this article is to make strings in an array become keys in objects within a new array in JavaScript. Let's consider a simple array: let array = ['bike', 'car']; We want to transform this array into a new array where each string becomes a key in an object with an empty array as its value: let newArray = [{bike: []}, {car: []}]; Let's explore different methods to accomplish this transformation in JavaScript. Using map() Method The map() method creates a new array ...

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How to detect and replace all the array elements in a string using RegExp in JavaScript? 

Yaswanth Varma
Yaswanth Varma
Updated on 15-Mar-2026 1K+ Views

In JavaScript, you can detect and replace all array elements in a string using regular expressions (RegExp). This technique is useful for text processing, content filtering, and dynamic string manipulation where you need to replace multiple values at once. Let's explore different methods to detect and replace all array elements in a string using RegExp in JavaScript. Using RegExp with join() Method The most efficient approach is to create a single regular expression pattern by joining array elements with the OR operator (|). Syntax new RegExp(array.join('|'), 'flags') Example: Basic Replacement ...

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Substitute random items in a JavaScript array?

Yaswanth Varma
Yaswanth Varma
Updated on 15-Mar-2026 466 Views

To substitute random items in a JavaScript array, you can use Math.random() along with map() to replace selected elements with new values while keeping others in their original positions. For example, if you have an array [m, n, o, p] and want to replace two random items with 'a', the result might be [a, a, o, p] where m and n were randomly selected and replaced. Using Math.random() Method The Math.random() method returns a pseudo-random number between 0 (inclusive) and 1 (exclusive). It's used to generate random indices for array element selection. Syntax Math.random(); ...

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How do you display JavaScript datetime in 12hour AM/PM format?

Yaswanth Varma
Yaswanth Varma
Updated on 15-Mar-2026 4K+ Views

The most practical way to display datetime for efficient time analysis is in a 12-hour AM/PM format. This method clarifies the distinction between morning and evening, making times like "2:30 PM" more intuitive than "14:30" in 24-hour format. This article will explain various methods for displaying JavaScript datetime in 12-hour AM/PM format. Using the toLocaleString() Method The toLocaleString() method returns a formatted date string according to the specified locale and options. It's the most straightforward approach for 12-hour format conversion. Syntax Date.toLocaleString(locales, options) Parameters locales − Language/region ...

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Sorting an array that contains undefined in JavaScript?

Yaswanth Varma
Yaswanth Varma
Updated on 15-Mar-2026 3K+ Views

In JavaScript, arrays can contain undefined values which require special handling during sorting. By default, the sort() method converts all elements to strings, placing undefined values at the end of the sorted array. Let's explore different approaches to sort arrays containing undefined values effectively. Default Behavior with sort() When using the basic sort() method on arrays with undefined, JavaScript automatically places undefined values at the end: var namearr = ["Zebra", "Yatch", undefined, "Egg", undefined]; namearr.sort(); ...

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How to get substring between two similar characters in JavaScript?

Yaswanth Varma
Yaswanth Varma
Updated on 15-Mar-2026 4K+ Views

In JavaScript, extracting a substring between two similar characters is a common task when parsing strings. This article explores different methods to achieve this using built-in string methods. Understanding String Methods Before diving into the solution, let's understand the key methods we'll use: The substring() method extracts characters between two indices and returns a new string without modifying the original. Syntax string.substring(start, end) The split() method divides a string into an array of substrings based on a specified separator. Syntax string.split(separator, limit) Method 1: Using split() ...

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Adding a unique id for each entry in JSON object in JavaScript

Nikitasha Shrivastava
Nikitasha Shrivastava
Updated on 15-Mar-2026 5K+ Views

In this problem statement, our task is to add a unique id for every object entry in a JSON object with the help of JavaScript. We will use a loop and a variable to store the id for each object in the JSON object. Understanding the Problem Statement The problem statement is to write a function in JavaScript that adds a unique id to every item in the given JSON object. For example, if we have: let obj = { "entry1": {empName: "A", age: 25}, "entry2": {empName: "B", age: 30} ...

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Algorithm to get the combinations of all items in array JavaScript

Nikitasha Shrivastava
Nikitasha Shrivastava
Updated on 15-Mar-2026 4K+ Views

In this problem statement, our task is to get the combinations of all items in an array with the help of Javascript functionalities. We can use a recursive approach that iteratively adds items to a running list of combinations. Understanding the Problem The goal is to write a function in Javascript that finds all possible combinations of elements in an array. For example, if we have an array [1, 2, 3], the combinations would be: [ [], [1], [2], [3], [1, 2], [1, ...

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