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To set a background image to be fixed in JavaScript, use the backgroundAttachment property. This CSS property controls whether the background image scrolls with the content or remains fixed in the viewport. Understanding backgroundAttachment The backgroundAttachment property accepts three values: "scroll" - Background scrolls with content (default) "fixed" - Background stays fixed relative to viewport "local" - Background scrolls with element's content Syntax element.style.backgroundAttachment = "fixed"; Example: Fixed Background Image This example demonstrates how to set a fixed background image that won't scroll with the page content: ... Read More
The element can be used to include an external style sheet file in your HTML document. An external style sheet is a separate text file with .css extension. You define all the Style rules within this text file and then you can include this file in any HTML document using element. Creating an External CSS File Consider a simple style sheet file with a name new.css having the following rules: h1, h2, h3 { color: #36C; font-weight: normal; letter-spacing: .4em; ... Read More
Mark and Sweep Algorithm The Mark and Sweep algorithm is JavaScript's primary garbage collection method that identifies objects "which are unreachable" rather than objects "which are no longer needed". This algorithm is an improvement over the Reference-counting algorithm and solves the circular reference problem. How Mark and Sweep Works The algorithm operates in three important steps: Root Identification: The algorithm starts from "roots" - global variables accessible in the code. In browsers, the window object acts as the primary root. Marking Phase: The algorithm traverses from roots to find ... Read More
Merge Sort and Quick Sort are two popular divide-and-conquer sorting algorithms in JavaScript. While both are efficient, they differ in their approach, stability, and performance characteristics. Merge Sort Overview Merge Sort is a stable sorting algorithm that recursively divides the array into halves until each sub-array contains a single element, then merges them back in sorted order. It guarantees O(n log n) time complexity in all cases but requires additional space for merging. Quick Sort Overview Quick Sort selects a pivot element and partitions the array around it, placing smaller elements to the left and larger ... Read More
Data Driven and Keyword Driven frameworks are two popular approaches in test automation. Understanding their differences helps choose the right framework for your testing needs. Data Driven Framework In data driven testing, we run tests on multiple data sets using parameterization. The data acts as input to the test script logic, with each data set representing a separate test case. The framework revolves around data maintained in external files (Excel, CSV, JSON) which is updated for individual test cases without changing the core test script logic. Example: Data Driven Login Test // Sample data ... Read More
The File and FileReader APIs in JavaScript allow web applications to read and process files selected by users. The File object represents file information, while FileReader enables reading file contents asynchronously. File Object Properties When a user selects a file through an input element, you get access to a File object with these key properties: name - The file's name size - File size in bytes type - MIME type of the file lastModified - Last modification timestamp FileReader Methods FileReader provides several methods to read file contents: readAsText() - Reads ... Read More
Let's say, we have an array of arrays that contains some elements like this − const arr = [3, 5, 7, 2, [4, NaN, null, 4, 8, [3, undefined, 24, null], null, 5, 1], NaN, 45, 2, 1]; Our job is to write a recursive function that takes in this nested array and replaces all the falsy values inside the array (NaN, undefined and null) with 0. Understanding Falsy Values In JavaScript, falsy values include: null undefined NaN ... Read More
In JavaScript, there's no true associative array like in other languages. Instead, you use objects or arrays of objects to achieve similar functionality. JavaScript objects act as associative arrays where you can use string keys to access values. What are Associative Arrays? Associative arrays use named keys instead of numeric indexes. In JavaScript, regular arrays have numeric indexes, but objects provide key-value pairs that function like associative arrays. Method 1: Using Objects The most common approach is using plain JavaScript objects: // Creating an associative array using object var customer = { ... Read More
We are required to write a JavaScript function that takes in an array of positive as well as negative Numbers and changes the positive numbers to corresponding negative numbers and the negative numbers to corresponding positive numbers in place. Let's write the code for this function — Example Following is the code — const arr = [12, 5, 3, -1, 54, -43, -2, 34, -1, 4, -4]; const changeSign = arr => { arr.forEach((el, ind) => { arr[ind] *= -1; ... Read More
In this tutorial, we will learn how to get the hash part of the href attribute of an area in JavaScript. The HTML element establishes an area within an image map with predetermined clickable zones. An image map allows you to correlate geometric regions of a picture with hypertext links. This element can only be used within the element. The href property gives the area's hyperlink target. The element is not a hyperlink if the href attribute is not present. Following is a method used to get the href attribute's hash part of an ... Read More