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.
Articles
JavaScript, page 19 of 19
JavaScript is the working language behind most of my front‑end writing, from small browser behaviours to application state and asynchronous code. These articles favour the mechanism behind a feature over a clever trick, whether the subject is callbacks, async code, or a language edge that only becomes obvious in production.
Get the Number of Years Between Two Dates with PHP and 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.
Writing JavaScript That Still Works Without jQuery. Writing JavaScript That Still Works Without jQuery
Write small JavaScript behaviours that work without jQuery, covering selectors, classes, events, feature checks, fallbacks, and easier migration paths.
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.
Progressive Enhancement with jQuery. Progressive Enhancement with jQuery
Use jQuery as an enhancement layer whilst keeping links, forms, navigation, and core page content usable without JavaScript, late scripts, or plugin failure.
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!
Button vs. Link: Native Semantics Before Custom Click Handlers. Button vs. Link: Native Semantics Before Custom Click Handlers
Use links for navigation and buttons for actions, preserving native focus and keyboard behaviour before adding custom click handlers or ARIA roles.
Safe DOM Insertion and Sanitisation. Safe DOM Insertion and Sanitisation
Choose between textContent and innerHTML safely, handle Internet Explorer's innerText fallback, and know exactly when untrusted HTML needs sanitisation.
Why removeeventlistener() Needs the Same Function Reference. Why
removeeventlistener()Needs the Same Function ReferenceUnderstand why removeEventListener needs the original callback reference, how anonymous functions differ, and what Internet Explorer required in 2010.
