JavaScript Tutorials

  • By
    Immediately Executing setInterval with JavaScript

    Employing setInterval for condition polling has really been useful over the years. Whether polling on the client or server sides, being reactive to specific conditions helps to improve user experience. One task I recently needed to complete required that my setInterval immediately execute and...

  • By
    JavaScript String replaceAll

    Replacing a substring of text within a larger string has always been misleading in JavaScript. I wrote Replace All Occurrences of a String in JavaScript years ago and it's still one of my most read articles. The confusion lies in that replace only...

  • By
    navigator.clipboard API

    Reading from and writing to the user's clipboard can be both a very useful and dangerous capability. Used correctly and it's a huge convenience to the user; used dubiously and the user could suffer catastrophic consequences. Imagine a wrong account number or wallet address...

  • By
    Array.prototype.at

    Working with arrays is an essential skill in any programming language, especially JavaScript, as we continue to rely on external data APIs. JavaScript has added methods like find and `findIndex recently, but one syntax I love from languages like Python is retrieving values by negative indexes.When...

  • By
    Command Line trash

    One of the first commands you learn when experimenting with command line is rm, the utility for deleting files and directories. Deletion is a core computer UI operation but operating systems use a "Trash" paradigm, where files are stored before truly deleted. With the...

  • By
    How to Create a UUID in JavaScript

    The UUID identifier has been used in programming since the days a baby-faced David Walsh became a professional software engineer. My first exposure to UUIDs was via a ColdFusion app I inherited and ... the less we say about that the better. In any...

  • By
    AggregateError

    One of the big themes of the web these days is concurrency, which leads to accomplishing tasks asynchronously. In doing so, the possibility of multiple errors can occur. Instead of providing a generic error, optimally you'd provide a wealth of error information. TheAggregateError...

  • By
    jq for JSON

    I old enough to remember when we thought XML was going to change the programming world...then JSON saved us from that hell. Parsing and querying JSON data is fundamental task we've all coded for, but sometimes I just want to get some data locally with minimal...

  • By
    React usePrevious Hook

    Hooks are essential for the functional component pattern in React. One frequent logic comparison with class components was comparing a previous prop value with a current prop value via lifecycle methods. So what's an easy pattern for duplicating previous value comparisons in functional components?The useRef and...

  • By
    onInput Event

    Coding HTML forms has been painful my entire career. Form controls look different between operating systems and browsers, coding client side and server side validation is a nightmare, and inevitably you forget something somewhere along the line. Some behaviors don't act the way you'd...