How to Read JavaScript Errors and Stack Traces
How to read JavaScript errors and stack traces in the browser, including common error types, line numbers, call stacks, and a practical debugging workflow.
Articles
JavaScript, page 17 of 17
JavaScript is probably one of the most‑used programming languages in the world, and a cornerstone of front‑end (and more general) web development. It enables the development of interactivity and features that HTML and CSS alone simply cannot, and includes more advanced concepts like closures, callbacks, and asynchronous programming.
Below you will find a subset of articles from my blog specifically about JavaScript. This is an area that I have worked with for many years, and have managed to write about quite a few times. There are three hundred collected together for you below.
How to Read JavaScript Errors and Stack Traces. 
Pass by Value vs. Reference in JavaScript. Pass by Value vs. Reference in JavaScript
Pass by value vs. reference in JavaScript explained clearly, including why objects seem shared, how reassignment differs from mutation and common beginner bugs.
Accessing a Random Element from an Array Using JavaScript. Accessing a Random Element from an Array Using JavaScript
Pick a random array element in JavaScript with Math.random(), safe index calculation, reusable helpers, and notes on real interface randomisation.
Get the Number of Years Between Two Dates with PHP and JavaScript. Get the Number of Years Between Two Dates with PHP and JavaScript
A common web development task: get the number of years between two dates. I discuss how to do this with PHP in the back‑end, or front‑end with JavaScript.
Using data‑* Attributes and dataset in JavaScript. Using
data‑*Attributes anddatasetin JavaScriptUse data attributes and dataset in JavaScript to connect HTML and behaviour cleanly, handle camelCase mapping, event delegation, and string values.
DOM Traversal: closest() in Vanilla JavaScript and jQuery. DOM Traversal:
closest()in Vanilla JavaScript and jQueryUse closest() for DOM traversal in jQuery and vanilla JavaScript, replacing manual parent walking in menus, click handlers, and interactive UI cleanly.
Using classList in JavaScript: add(), remove(), toggle(), and contains(). Using
classListin JavaScript:add(),remove(),toggle(), andcontains()Use classList in JavaScript for add(), remove(), toggle(), and contains(), with cleaner DOM state updates, validation examples, and className cautions.
Handling Click Events in JavaScript. Handling Click Events in JavaScript
Handle click events in JavaScript with onclick and addEventListener, including vanilla alternatives to jQuery, event targets, and common interaction patterns.
DOMContentLoaded vs. load in JavaScript. DOMContentLoadedvs.loadin JavaScriptCompare DOMContentLoaded and load in JavaScript, including parsing, asset loading, script timing, selector failures, and when each event is useful.
Why querySelector Returns null in JavaScript. Why
querySelectorReturnsnullin JavaScriptDebug querySelector returning null in JavaScript by checking selector syntax, DOM timing, missing elements, search scope, and querySelectorAll differences.
How to Check an Element Exists with and Without jQuery. How to Check an Element Exists with and Without jQuery
Check whether an element exists with jQuery or vanilla JavaScript before running DOM code, avoiding null errors and fragile client‑side behaviour.
A Simple Popup Window Using jQuery. A Simple Popup Window Using jQuery
Opening a new browser window programmatically on‑click is very simple to achieve with jQuery, and no more complex to achieve with vanilla JavaScript too!
