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We need to write a function that takes in a string file path and returns the filename. Filename usually lives right at the very end of any path, although we can solve this problem using regex but there exists a simpler one-line solution to it using the string split() method of JavaScript and we will use the same here. Let's say our file path is − "/app/base/controllers/filename.js" Using split() Method Following is the code to get file name from string path − const filePath = "/app/base/controllers/filename.js"; const extractFilename = (path) => { ... Read More
We need to write a JavaScript function that takes a number and returns the nearest power of 2. A power of 2 is any number that can be expressed as 2n where n is a whole number (1, 2, 4, 8, 16, 32, 64, 128, 256, etc.). For example, if the input is 365, the output should be 256 because 256 (28) is closer to 365 than the next power of 2, which is 512 (29). Algorithm Explanation The algorithm works by: Starting with base = 1 (20) Doubling the base until it exceeds the input ... Read More
When working with strings containing digits, you often need to count how many times each digit appears. This is a common programming task that can be solved efficiently using JavaScript objects. Suppose we have a string with digits like this: const str = '11222233344444445666'; We need to write a JavaScript function that takes this string and returns an object representing the count of each digit in the string. For this string, the expected output should be: { "1": 2, "2": 4, "3": 3, "4": ... Read More
To perform automated unit testing in JavaScript, Unit.js is a cross-platform open-source unit testing framework that provides a simple and intuitive API for testing JavaScript applications. What is Unit.js? Unit.js is a JavaScript testing framework that works in both Node.js and browsers. It offers a fluent interface for writing readable test assertions and supports various testing patterns. Basic Syntax Unit.js uses a chainable syntax where you specify the data type and then chain assertion methods: test.dataType(value).assertionMethod(expectedValue); Simple String Testing Example Here's a basic example of testing a string value: ... Read More
Creating a full-page drag and drop interface allows users to drop files anywhere on the webpage. This involves detecting drag events and showing a drop zone overlay. HTML Structure First, create the basic HTML with a drop zone overlay: #dropZone { position: fixed; top: 0; ... Read More
The _.union() method from the Underscore.js library creates a new array containing unique values from multiple input arrays. It performs a union operation, removing duplicates while preserving the original order of first occurrence. Syntax _.union(array1, array2, ...arrayN); Parameters array1, array2, ...arrayN: Two or more arrays to be combined. The method accepts any number of arrays as arguments. Return Value Returns a new array containing all unique values from the input arrays, maintaining the order of first occurrence. Example with Numbers In the following example, _.union() combines multiple arrays and removes ... Read More
The JavaScript BOM (Browser Object Model) Window screen object provides detailed information about the user's display screen. This object is useful for creating responsive web applications and gathering display specifications. Screen Object Properties Property Description screen.width Returns the total screen width in pixels ... Read More
Let's say we are required to write a function that takes in an array and changes the id attribute of first n divs present in a particular DOM according to corresponding values of this array, where n is the length of the array. We will first select all divs present in our DOM, iterate over the array we accepted as one and only argument and assign the corresponding id to each div. Basic Example Here's the HTML structure we'll work with: Setting Attributes in Loop ... Read More
To un-nest an array of objects in JavaScript, you can use the map() method to restructure nested data into a flatter format. This is useful when you have deeply nested objects and want to extract specific properties to create a simpler structure. Problem: Nested Object Structure Let's say you have an array of student objects where subject details are nested inside each student: const studentDetails = [ { "studentId": 101, "studentName": "John", ... Read More
We are given the lengths of three sides of a triangle and we are required to write a function that returns the area of the triangle using the length of its sides. Heron's Formula We can calculate the area of a triangle if we know the lengths of all three sides, using Heron's formula: Step 1 − Calculate "s" (half of the triangle's perimeter): s = (a + b + c) / 2 Step 2 − Then calculate the Area using Heron's formula: A = √(s(s-a)(s-b)(s-c)) Syntax ... Read More