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There are three effective methods to read JSON files in JavaScript using fetch(), import statements, and require(). This article covers practical examples for both browser and Node.js environments. JSON (JavaScript Object Notation) is a lightweight data interchange format that's easy for humans to read and write. In this article, we'll explore three different approaches to reading JSON files in JavaScript: Approaches to Read JSON file Using the fetch() method (Browser) Using the import statement (ES6 Modules) Using the require() method (Node.js) Each method ... Read More
Problem We need to write a JavaScript function that takes a string and encodes it using a compression format. The function should compare the encoded string with the original and return whichever is smaller. The encoding rule is: n[s], where s inside the square brackets is being repeated exactly n times. For example, "ddd" can be encoded to "3[d]", but since "3[d]" has 4 characters while "ddd" has only 3, the function should return "ddd". Example Input and Output For the input string: 'aabcaabcd' The expected ... Read More
We can create a Polygon object by creating an instance of fabric.Polygon. A polygon object can be characterized by any closed shape consisting of a set of connected straight line segments. Since it is one of the basic elements of FabricJS, we can also easily customize it by applying properties like angle, opacity etc. In order to convert a polygon object into HTMLCanvasElement we use the toCanvasElement method. It returns the DOM element of type HTMLCanvasElement, an interface which inherits its properties and methods from the HTMLElement interface. Syntax toCanvasElement( options: Object ): HTMLCanvasElement ... Read More
There are different methods to change the path of an image given to the src attribute of an img element in HTML document using JavaScript and jQuery. Method of changing the src attribute of an img element using JavaScript: Use the src property in JavaScript. Methods of changing the src attribute of an img element using jQuery: Using attr() method Using prop() method Let us discuss each of the above listed methods of changing the src of an img element one by one in ... Read More
When working with hyphen-delimited strings containing negative numbers or ranges, simple split('-') won't work correctly because it treats every hyphen as a delimiter. We need regular expressions to distinguish between separating hyphens and negative number signs. The Problem Consider these strings with mixed content: var firstValue = "John-Smith-90-100-US"; var secondValue = "David-Miller--120-AUS"; Using split('-') would incorrectly split negative numbers and ranges, giving unwanted empty strings and broken values. Solution Using Regular Expression We use a lookahead pattern to split only at hyphens that precede letters or number ranges: var firstValue ... Read More
In JavaScript, objects themselves cannot be sorted since their properties don't have a guaranteed order. However, we can extract the values from a JSON object and sort them into an array. Suppose we have an object like this: const obj = { key1: 56, key2: 67, key3: 23, key4: 11, key5: 88 }; We need to write a JavaScript function that takes this object and returns a sorted array of its values: const arr = [11, 23, 56, ... Read More
Backtracking is a powerful algorithmic pattern for solving constraint satisfaction problems. In this grid path problem, we need to find all possible paths from start to end that visit every walkable square exactly once. Problem Definition Given a 2D grid with different square types, find the number of unique paths from start to end: 1 represents the starting square (exactly one) 2 represents the ending square (exactly one) 0 represents empty squares we can walk over -1 represents obstacles we cannot walk over ... Read More
Sometimes you receive data in a complex JSON array format with key-value pairs, but need to convert it to a simple flat object structure for easier access and manipulation. Problem Structure Consider this complex JSON array with nested key-value objects: const arr = [{ "key": "name", "value": "john" }, { "key": "number", "value": "1234" }, { "key": "price", "value": ... Read More
Taking a screenshot of a div element in JavaScript requires converting HTML elements to an image format. Since JavaScript cannot directly capture DOM elements as images, we use third-party libraries like html2canvas to achieve this functionality. The html2canvas library renders DOM elements onto a canvas element, which can then be converted to an image or downloaded. This approach works by parsing the CSS styles and creating a visual representation of the element. Installation and Setup To use html2canvas, include it via CDN or install it through npm: // Via CDN (add to HTML head) ... Read More
A convex polygon is a polygon where all interior angles are less than 180°. In a convex polygon, all vertices point "outward" and no line segment between any two points inside the polygon extends outside the polygon. Problem Statement We need to write a JavaScript function that takes an array of coordinates representing vertices of a polygon. Each coordinate is an array containing two numbers [x, y] representing a point on a 2D plane. The function should return true if the polygon is convex, false otherwise. For example, if the input is: const arr = ... Read More