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Articles by Ayush Gupta
Page 4 of 44
What is the use of sinon.js?
SinonJS provides standalone test spies, stubs and mocks for JavaScript unit testing. It helps create fake objects and functions to isolate and test code in controlled environments. What is SinonJS? SinonJS is a testing library that provides utilities for creating test doubles. These help you test code in isolation by replacing dependencies with controlled fake implementations. Core Features SinonJS offers three main types of test doubles: Spies — Track function calls without changing behavior. They record how functions are called. Stubs — Replace functions with controlled implementations. You can define what they return or ...
Read MoreExplain the event flow process in Javascript
The JavaScript event flow process describes how events propagate through the DOM tree when an event occurs. This process involves three key phases: capturing, target, and bubbling. Event Flow Phases Event Capturing: The event starts from the document root and travels down to the target element. Event Target: The actual DOM element where the event occurred. Event Bubbling: The event travels back up from the target element to the document root. ...
Read MoreHow to allocate memory in Javascript?
Regardless of the programming language, memory life cycle is pretty much always the same: Allocate the memory you need Use the allocated memory (read, write) Release the allocated memory when it is not needed anymore The second part is explicit in all languages. Use of allocated memory needs to be done by the developer. The first and last parts are explicit in low-level languages like C but are mostly implicit in high-level languages like JavaScript. Hence there is no explicit way to allocate or free up memory in JavaScript. Just initializing objects allocates memory ...
Read MoreLow level difference between Slice and Splice methods in Javascript
The slice() and splice() methods are often confused due to their similar names, but they behave very differently. Understanding their key differences is crucial for array manipulation in JavaScript. Key Differences splice() modifies the original array by adding, removing, or replacing elements and returns an array of removed items. slice() creates a shallow copy of a portion of the array without modifying the original and returns the extracted elements. Syntax Comparison // splice syntax array.splice(startIndex, deleteCount, item1, item2, ...) // slice syntax array.slice(startIndex, endIndex) Example: Demonstrating the Difference ...
Read MoreDifference between shift() and pop() methods in Javascript
The shift() method removes the element at the first index (index 0) and shifts all remaining elements down by one position, then returns the removed value. If the array is empty, it returns undefined. The pop() method removes the last element from an array and returns that element. This method changes the length of the array. Syntax array.shift() // Removes first element array.pop() // Removes last element Example: Comparing shift() and pop() let fruits = ['apple', 'mango', 'orange', 'kiwi']; let fruits2 = ['apple', 'mango', 'orange', 'kiwi']; ...
Read MoreDifference between push() and unshift() methods in javascript
JavaScript arrays provide two methods for adding elements: push() adds elements at the end, while unshift() adds elements at the beginning. Both methods modify the original array and return the new array length. push() Method The push() method adds one or more elements to the end of an array and returns the new length of the array. let fruits = ['apple', 'mango', 'orange']; console.log("Original array:", fruits); let newLength = fruits.push('kiwi'); console.log("After push():", fruits); console.log("New length:", newLength); Original array: [ 'apple', 'mango', 'orange' ] After push(): [ 'apple', 'mango', 'orange', 'kiwi' ] New ...
Read MoreWhich algorithm does the JavaScript Array#sort() function use?
JavaScript's Array.sort() method doesn't mandate a specific sorting algorithm in the ECMAScript specification. This gives JavaScript engines freedom to choose the most efficient implementation for their environment. Engine-Specific Implementations Different JavaScript engines use different sorting strategies based on performance optimizations and array characteristics. Mozilla Firefox (SpiderMonkey) SpiderMonkey primarily uses merge sort, which provides stable O(n log n) performance. The implementation can be found in Mozilla's C codebase. Chromium/WebKit (V8 Engine) V8 uses a hybrid approach called Timsort (based on merge sort and insertion sort) for optimal performance across different data patterns. The algorithm selection depends on: ...
Read MoreDifference between regular functions and arrow functions in JavaScript
According to MDN, an arrow function expression is a syntactically compact alternative to a regular function expression, although without its own bindings to the this, arguments, super, or new.target keywords. Arrow function expressions are ill suited as methods, and they cannot be used as constructors. There are three key differences between regular functions and arrow functions in JavaScript that affect how they behave in your code. No Own this Bindings Arrow functions do not have their own this value. The value of this inside an arrow function is always inherited from the enclosing scope, while regular functions ...
Read MoreWhy is javascript called Richer Interface?
JavaScript is called a "Richer Interface" because it enables developers to create highly interactive and feature-rich web applications that go far beyond simple static content. Unlike basic HTML and CSS, JavaScript provides access to powerful APIs that can interact with multimedia, device hardware, and user data. Key Features that Make JavaScript Rich Graphics and Animation JavaScript can draw and manipulate graphics through Canvas API and WebGL, allowing developers to create games, data visualizations, and interactive animations directly in the browser. const canvas = document.getElementById('myCanvas'); const ctx = canvas.getContext('2d'); // Draw a colorful rectangle ...
Read MoreWhat is "undefined x 1" in JavaScript?
The "undefined x 1" notation is not a JavaScript feature but Chrome's way of displaying sparse arrays with uninitialized elements. Instead of showing every undefined value, Chrome uses compact notation for better readability. What Creates "undefined x n" When you create an array with the Array() constructor or have gaps in array indexes, Chrome displays uninitialized slots as "undefined x count": console.log(Array(5)); [undefined × 5] Sparse Arrays Example Arrays with missing indexes also show this notation: let arr = [1, , , 4]; // Missing elements at ...
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