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The eval() function in JavaScript allows the execution of code stored as a string. It can be used to fetch specific values dynamically, but be careful, as it can have security risks and affect performance. This article will guide you on how to use eval() to get specific values and why you should generally avoid using eval(). How eval() Works The eval() function takes a string as an argument and evaluates it as JavaScript code. For example: console.log(eval("2 + 2")); // Output: 4 console.log(eval("'Hello' + ' World'")); // Output: Hello World 4 Hello World ... Read More
To filter null values from an array in JavaScript, use the filter() method. This method creates a new array containing only elements that pass a specified condition. Syntax array.filter(callback) Method 1: Using Boolean Constructor The simplest approach is to pass Boolean as the filter callback, which removes all falsy values including null, undefined, and empty strings. var names = [null, "John", null, "David", "", "Mike", null, undefined, "Bob", "Adam", null, null]; console.log("Before filtering:"); console.log(names); var filteredNames = names.filter(Boolean); console.log("After filtering null/falsy values:"); console.log(filteredNames); Before filtering: [ ... Read More
We are required to write a function that, given a number, say, 123, will output an array − [100, 20, 3] Basically, the function is expected to return an array that contains the place value of all the digits present in the number taken as an argument by the function. We can solve this problem by using a recursive approach. Example Following is the code − const num = 123; const placeValue = (num, res = [], factor = 1) => { if(num){ ... Read More
In this tutorial, programmers will learn to change the font size of text using JavaScript. Many applications allow users to change the font size according to their requirements. We need to change the default font size using JavaScript to achieve that. Before we move ahead with the tutorial, let's learn what values we can assign to the font size. Different Values for Font Size We can assign the below values to the font size of any element. Every value changes the font size differently: xx-large | x-large | large | medium | small ... Read More
To return the "time" portion of the Date as a string, using the current locale's conventions, use the toLocaleTimeString() method. The toLocaleTimeString() method relies on the underlying operating system in formatting dates. It converts the date to a string using the formatting convention of the operating system where the script is running. For example, in the United States, the time appears in 12-hour format with AM/PM, whereas in many European countries, it appears in 24-hour format. Syntax date.toLocaleTimeString([locales], [options]) Parameters locales (optional): A string or array of strings representing locale identifiers (e.g., ... Read More
In this tutorial, we will learn how to set the indentation of the first line of text with JavaScript. The indentation of the first line of a text is a common way to start a new paragraph. To set the indentation, use the textIndent property. To set the indentation of the first line of text with JavaScript, we will discuss two different ways − Using the style.textIndent Property Using the style.setProperty Method Using the style.textIndent Property The style.textIndent property of an element is used to set the ... Read More
JavaScript drag and drop functionality provides an intuitive way to move elements within web pages. While the HTML5 Drag and Drop API works well on desktop, touch devices require additional handling to ensure proper functionality. Basic Drag and Drop Concepts To make an element draggable in HTML5, add the draggable="true" attribute to the element. By default, images and text selections are draggable, but other elements need this attribute. Drag me Drag and Drop Events The drag and drop process involves two sets of events: Events on draggable elements: dragstart - Fires ... Read More
HTML5 audio elements don't have a built-in stop button, but you can create one by combining the pause() method with resetting the currentTime property. Basic Stop Function To stop audio playback, pause the audio and reset its current time to zero: Stop function stopAudio() { var myPlayer = document.getElementById('myAudio'); myPlayer.pause(); myPlayer.currentTime = 0; } Complete Example with Play/Stop Controls Play Stop var audio = document.getElementById('audioPlayer'); function playAudio() { ... Read More
The ArrayBuffer.isView() static method determines whether a given value is an ArrayBuffer view. ArrayBuffer views include typed arrays (like Int32Array, Float64Array) and DataView objects. Syntax ArrayBuffer.isView(value) Parameters value: The value to test whether it's an ArrayBuffer view. Return Value Returns true if the value is an ArrayBuffer view (typed array or DataView), false otherwise. Example 1: Testing Typed Arrays ArrayBuffer.isView() Example // Create typed arrays ... Read More
The Object.is() method determines whether two values are strictly equal, providing more precise comparison than the regular equality operators. Syntax Object.is(value1, value2) Parameters value1: The first value to compare value2: The second value to compare Return Value Returns true if both values are the same, false otherwise. How Object.is() Determines Equality Two values are considered the same when they meet these criteria: Both are undefined or both are null Both are true or both ... Read More