Questions
JavaScript questions
Choose a question page, learn the concept, then test your understanding with a quiz.
How to Create a GUID / UUID in JavaScript
Learn how to generate GUIDs and UUIDs in JavaScript safely, including browser support, randomness, and practical examples.
How to Create an Array from 1 to N in JavaScript
Learn how to create a JavaScript array containing numbers from 1 to N using loops, Array.from, keys, and practical patterns.
How to Disable and Enable an Input with jQuery
Learn the correct way to disable and enable form inputs with jQuery using prop(), attr(), and plain JavaScript examples.
How to Display a JavaScript Object as a String
Learn how to display JavaScript objects with console.log, JSON.stringify, and readable formatting for alerts, debugging, and user interfaces.
How to Empty an Array in JavaScript
Learn how to empty a JavaScript array using length, splice, reassignment, and pop, including how shared references affect each approach.
How to Encode a URL in JavaScript for Query Strings
Learn how to safely encode URLs in JavaScript for GET parameters using encodeURIComponent, with examples and common mistakes.
How to Format Numbers as Currency Strings in JavaScript
Learn how to format numbers as currency strings in JavaScript using toFixed and Intl.NumberFormat with clear examples.
How to Format a Date in JavaScript
Learn how to format JavaScript Date objects into strings like 10-Aug-2010 using built-in methods and simple custom formatting.
How to Get Query String Values in JavaScript
Learn how to read query string parameters in JavaScript using URLSearchParams and classic approaches, with examples and common mistakes.
How to Get Selected Text from a Select Box in jQuery
Learn how to get the selected option text from a select box in jQuery, with examples, common mistakes, and practical usage patterns.
How to Get a Timestamp in JavaScript
Learn how to get the current timestamp in JavaScript, including Unix time, milliseconds, seconds, and common date pitfalls.
How to Get the Current Date in JavaScript
Learn how to get the current date in JavaScript using Date, format it, and understand common mistakes with practical examples.
How to Get the Current URL in JavaScript
Learn how to get the current page URL in JavaScript using window.location, with examples, common mistakes, and practical use cases.
How to Get the Length of a JavaScript Object
Learn how to count properties in a JavaScript object using Object.keys(), when it works, and common mistakes to avoid.
How to Get the Selected Value from a Dropdown in JavaScript
Learn how to get the selected value from an HTML dropdown using JavaScript, with examples, common mistakes, and practical use cases.
How to Include One JavaScript File in Another JavaScript File
Learn how JavaScript files are loaded and how to share code using script tags and ES modules in modern JavaScript.
How to Insert an Item into an Array at a Specific Index in JavaScript
Learn how to insert values into a JavaScript array at a specific index using splice, with examples, pitfalls, and real-world use cases.
How to Iterate Through Object Properties in JavaScript
Learn how for...in works in JavaScript, why the loop variable receives object property names, and how to iterate safely.
How to Loop Through a JavaScript Object of Nested Objects
Learn how to iterate through a JavaScript object whose values are objects, using for...in, Object.keys, and Object.entries.
How to Loop Through a JavaScript Object: Keys, Values, and Entries
Learn how to loop through a JavaScript object and access its keys and values using for...in, Object.keys, Object.values, and Object.entries.