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Articles by mkotla
Page 3 of 8
How to write a global error handler in JavaScript?
Global error handlers in JavaScript allow you to catch unhandled exceptions and errors that occur anywhere in your application. This is essential for debugging and providing better user experience. Using window.onerror The window.onerror event handler catches JavaScript runtime errors, including syntax errors and uncaught exceptions. Syntax window.onerror = function(message, source, lineno, colno, error) { // Handle the error return true; // Prevents default browser error handling }; Parameters Parameter Description message Error message source URL of the script ...
Read MoreHow to call a JavaScript function on submit form?
The onsubmit event occurs when you try to submit a form. You can put your form validation against this event type. The following example shows how to use onsubmit. Here we are calling a validate() function before submitting a form data to the webserver. If validate() function returns true, the form will be submitted, otherwise it will not submit the data. Basic Syntax Method 1: Using onsubmit Attribute The most common approach is to use the onsubmit attribute directly in the form ...
Read MoreWhat is a default constructor in JavaScript?
In JavaScript classes, if you don't define a constructor method, the JavaScript engine automatically provides a default constructor. This default constructor is implicit and handles basic object initialization. What is a Default Constructor? A default constructor is an empty constructor that JavaScript creates automatically when no explicit constructor is defined in a class. It performs minimal initialization and, for derived classes, calls the parent constructor. Syntax For base classes, the default constructor is equivalent to: constructor() {} For derived classes (classes that extend another class), the default constructor is: constructor(...args) ...
Read MoreHow to define functions inside a function body in JavaScript?
To define functions inside a function body in JavaScript, you can use nested function declarations or function expressions. This creates closures that have access to the outer function's scope. Basic Nested Function Functions declared inside another function are only accessible within that parent function: function outerFunction() { function innerFunction() { console.log("Hello from inner function!"); } innerFunction(); // Call the nested function } outerFunction(); Hello from inner function! ...
Read MoreHow to redirect if JavaScript is not enabled in a browser?
To redirect if JavaScript is not enabled in the web browser, add a script to the tag. Let us say you need to redirect to index.php if JavaScript is not enabled. The Problem When JavaScript is disabled, users might see a broken or non-functional page. The tag provides a fallback solution to redirect users to a JavaScript-free version of your site. How It Works The tag only executes when JavaScript is disabled or unavailable. We can use it with CSS and meta refresh to redirect users seamlessly. Example Here's how you ...
Read MoreShould I include language="javascript" in my SCRIPT tags?
The language="javascript" attribute in HTML tags is deprecated and unnecessary in modern web development. Since HTML5, JavaScript is the default scripting language for browsers, making this attribute redundant. Why language="javascript" is No Longer Needed HTML5 standardized JavaScript as the default scripting language. Modern browsers automatically assume that any tag without a type attribute contains JavaScript code. Legacy Usage (Deprecated) In older HTML versions, the language attribute was used to specify the scripting language: document.write("Hello World!"); Modern Approach (Recommended) Simply use the tag ...
Read MoreHow to Line Breaks to JavaScript Alert?
To add line breaks to JavaScript alerts, you can use several escape sequences. The most common and cross-browser compatible approach is using for new lines. Common Line Break Characters JavaScript supports multiple line break characters: - Line feed (most common, works across browsers) \r - Carriage return + line feed (Windows style) \r - Carriage return (older Mac style) Using (Recommended) function displayAlert() { var msg = ...
Read MoreWhat does the leading semicolon in JavaScript libraries do?
In JavaScript libraries, you'll often see code that starts with a semicolon before an Immediately Invoked Function Expression (IIFE). This is a defensive programming practice to prevent concatenation errors. The Problem: Missing Semicolons When JavaScript files are concatenated together for production, missing semicolons in the previous file can cause syntax errors: // File 1 ends without semicolon var myVariable = "Hello World" // File 2 starts with IIFE - This would break! (function() { console.log("Library code"); })(); This concatenates to invalid JavaScript because the parser tries to call myVariable ...
Read MoreAnimate CSS column-rule property
The CSS column-rule property defines the line that appears between columns in a multi-column layout. You can animate this property to create dynamic visual effects by changing the rule's width, style, and color during the animation. Syntax selector { column-rule: width style color; animation: animation-name duration timing-function iteration-count; } Example: Animating Column Rule The following example demonstrates how to animate the column-rule property, changing its width and color − .container { ...
Read MoreStyle input type button with CSS
The input type button can be a submit button or reset button. With CSS, we can style any button on a web page to enhance its appearance and user experience. Syntax input[type=button] { property: value; } Example 1: Basic Button Styling The following example demonstrates how to style an input type button with background color, padding, and hover effects − input[type=button] { background-color: #ff6600; ...
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