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Named capture groups JavaScript Regular Expressions

AmitDiwan
AmitDiwan
Updated on 15-Mar-2026 238 Views

Named capture groups in JavaScript regular expressions allow you to assign names to captured groups, making your code more readable and maintainable. Instead of accessing groups by index, you can reference them by meaningful names. Syntax // Named capture group syntax /(?pattern)/ // Accessing named groups match.groups.name Basic Example Named Capture Groups const text = "The year I graduated was 2012."; ...

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Access previously iterated element within array.map in JavaScript?

AmitDiwan
AmitDiwan
Updated on 15-Mar-2026 389 Views

In JavaScript, you can access previously iterated elements within array.map() using the index parameter. The map() method provides both the current element and its index, allowing you to reference earlier elements in the array. Let's say the following is our array: var details = [ {subjectId:110, subjectName: 'Java' }, {subjectId:111, subjectName: 'Javascript' }, {subjectId:112, subjectName: 'MySQL' }, {subjectId:113, subjectName: 'MongoDB' } ]; Using Index to Access Previous Elements The key is to use the index parameter in the map() callback to access ...

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Replace commas with JavaScript Regex?

AmitDiwan
AmitDiwan
Updated on 15-Mar-2026 775 Views

In JavaScript, you can replace commas in strings using the replace() method combined with regular expressions. This is particularly useful when you need to replace specific comma patterns, such as the last comma in a string. Problem Statement Consider these example strings with commas: "My Favorite subject is, " "My Favorite subject is, and teacher name is Adam Smith" "My Favorite subject is, and got the marks 89" We want to replace the last comma in each string with " JavaScript". Using Regular Expression to Replace Last Comma The regular expression /, ...

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Neutralisation of strings - JavaScript

AmitDiwan
AmitDiwan
Updated on 15-Mar-2026 286 Views

In JavaScript, string neutralisation involves evaluating a string containing only '+' and '-' characters to determine the overall sign. The concept is based on mathematical sign multiplication: like signs produce '+', unlike signs produce '-'. How Neutralisation Works The neutralisation follows these rules: ++ results in + (positive × positive = positive) -- results in + (negative × negative = positive) +- or -+ results in - (positive × negative = negative) Example String Let's work with the following string: const str = '+++-+-++---+-+--+-'; Implementation Here's how to implement ...

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How do I display image in alert/confirm box in JavaScript?

Shubham Vora
Shubham Vora
Updated on 15-Mar-2026 5K+ Views

In this tutorial, we will learn to display images in alert or confirm boxes in JavaScript. The standard alert() method displays a simple dialog box with text and an OK button, but it doesn't support images directly. To create more attractive and informative dialogs with images, we have two main approaches: Creating a custom alert box using vanilla JavaScript Using jQuery's dialog() method Method 1: Creating a Custom Alert Box This approach involves creating a custom HTML div that mimics an alert box and can contain images, styled ...

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How to force a number to display in exponential notation?

Sravani S
Sravani S
Updated on 15-Mar-2026 1K+ Views

Use the toExponential() method to force a number to display in exponential notation, even if the number is in the range in which JavaScript normally uses standard notation. Syntax number.toExponential(fractionDigits) Parameters fractionDigits - An optional integer specifying the number of digits after the decimal point. Defaults to as many digits as necessary to specify the number. Return Value Returns a string representing the number in exponential notation. Example: Basic Usage You can force a number to display in exponential notation as follows: ...

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How to set all outline properties in a single declaration with JavaScript?

Paul Richard
Paul Richard
Updated on 15-Mar-2026 195 Views

To set all outline properties in one declaration, use the outline property. It sets the following properties: outline-width, outline-style, and outline-color. Syntax element.style.outline = "width style color"; Parameters The outline property accepts three values in any order: width - thickness (thin, medium, thick, or length value like 2px) style - line style (solid, dashed, dotted, double, groove, ridge, inset, outset) color - outline color (color name, hex, rgb, rgba) Example You can try to run the following code to learn ...

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Escaping/encoding single quotes in JSON encoded HTML5 data attributes

George John
George John
Updated on 15-Mar-2026 4K+ Views

When embedding JSON data in HTML5 data attributes, single quotes can break HTML parsing. JavaScript provides several methods to properly escape or encode single quotes to ensure valid HTML output. The Problem with Single Quotes in Data Attributes Single quotes inside JSON values can break HTML attribute parsing when the attribute itself uses single quotes: // Problematic - single quote breaks HTML

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Why Ember.js is the best javascript frame work?

Aman Kumar
Aman Kumar
Updated on 15-Mar-2026 315 Views

Ember.js is a powerful JavaScript framework that has maintained steady adoption among developers. According to recent surveys, approximately 6.3% of JavaScript developers currently use Ember, ranking it as the 4th most popular JavaScript framework for building complex web applications. Ember.js follows the MVVM (Model-View-View-Model) architectural pattern and is specifically designed for complex, multi-page applications. As an open-source framework, it provides a complete solution for data management and application flow, making it ideal for ambitious web projects. One of Ember's key strengths is its refined upgrade system that helps developers integrate new versions without breaking changes. This stability-focused approach ...

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Explain the callback Promise.finally in JavaScript

AmitDiwan
AmitDiwan
Updated on 15-Mar-2026 259 Views

The Promise.finally() method executes a callback function when a promise settles, regardless of whether it's fulfilled or rejected. This method is essential for cleanup operations and tasks that must run after promise completion. Syntax promise.finally(callback) Parameters callback: A function that executes when the promise settles. It receives no arguments and its return value is ignored. How It Works Unlike .then() and .catch(), the finally callback doesn't receive the promise's result or rejection reason. It simply indicates that the promise has completed. Example with Fetch API ...

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