Sometimes we would like to detect when the subtitles change in the playing video. This can be done by listening to the cuechange event on the 〈track〉element.

It is very common to access current this context inside jQuery AJAX's response callbacks (success or error). This tutorial describes 3 ways of doing this.

The Page Visibility API can be used to check whether a browser tab is active or not, i.e. if the page is in view or hidden from view.

Google Fonts can be loaded through Javascript using the Web Font Loader Library. Events are also triggered when fonts are being loaded, or when they are rendered.

A UNIX timestamp can be converted to the required date and time formats in Javascript using the Date() object and its methods.

List of nodes returned by querySelectorAll() can be looped through using the forEach() method of the returned NodeList object.

Whenever a Javascript module needs to be applied to HTML, we need to do it within a 〈script type=module〉 tag. However there are some difference in Javascript execution in this tag vs a normal 〈script〉tag.

Options of a dropdown 〈select〉element can be looped over its options property. This property gives a list of all 〈option〉elements inside it.

A script tag having type=module attribute specifies that it to be considered as a Javascript module. It may be importing other Javascript module(s) inside it and becomes a top-level module for the imported modules.

Loading Disqus' script files and comments on page load can lower down speed and performance of the page, specially in mobiles. A solution would be to use an Intersection Observer to lazily load Disqus.

The number of available logical processor cores in the device can be found with the navigator.hardwareConcurrency Javascript property. This number can be useful in knowing how many Web Workers can be executed in parallel.

KV Storage API is an asynchronous way to save data in the browser using Javascript Promises. Its asynchronous nature guarantees that the performance of the application is not impacted.

An anonymous async function can be defined using the Immediately-invoked Function Expression pattern for asynchronous functions.

A Javascript array can be converted to a string by using the join() method to join elements of the array separated by a given character or string.

QR codes have become really popular these days. In web pages QR Codes can be generated using the QRCode.js Javascript library.

The Constraint Validation API validates HTML forms on page load, and while typing on an input field. This seemingly confusing behavoiur to the user can be modified using a bit of CSS and Javascript.

Duplicate elements can be removed from a Javascript array using the Set data type. A Set object can be created from the array, and then the Set can be converted back to an array.

Function parameters can be initialized with a default value in the parameter list itself using ES6 default parameters.

The Number() method can be used to convert a string containing numeric characters to a number upon which mathematical operations can be done.

The Math.sign() is a new method introduced in ES6 that can be used to find whether a number is positive or negative or a zero.