Modern applications show lots of useful information right in the user interface. For example, you as a user want to see if something is due today and be notified about the event. As a developer you need to make sure you’re showing the right items for today. That’s …

Sometimes you want to check if a given date represents “yesterday”, the previous day of today. For example, this use-case appears in UI elements where you’re showing relative dates like “yesterday” instead of the YYYY-MM-DD format. This tutorial shows you how to detect whether a given date is yesterday! …

Formatting dates is a common task in application. Displaying due dates or birthdays is always connected to dates. A typical formatting for readable dates is the YYYY-MM-DD format. This tutorial shows you how to format a JavaScript date in the YYYY-MM-DD format. {{outline}} Formatting JavaScript Dates in YYYY-MM-DD Formatting dates …

Large numbers are hard to read. For example, what about “2014010167“? Is it 20 million, 200 million, or 2 billion? Yeah, we can’t read that number either and need to concentrate. What about “2014010_167”? Much better! JavaScript shipped a new feature called “numeric separator” to improve readability on …

You can dynamically compose objects in JavaScript. You may add a property depending on a configuration or not. For example, when creating a database model you may allow users to configure whether to add or skip timestamps like createdOn and updatedOn. Model instances won’t have timestamps if a user …

In some situations you want to check if a given value is an array (or something else). This may be a required check in your code when allowing single items or an array of items as a method argument. This tutorial walks you through the pitfalls of using typeof and …

Sometimes you need to check for the type of a variable before moving on with any processing. For example, you may want to validate a value to be an object before merging its properties with another object. This tutorial shows you how to confidently check whether a given value is …

JavaScript introduced the destructuring assignment back in 2015. The destructuring assignment is a way to unpack properties of an object or items from arrays into variables using a syntax that looks like objects or arrays. This tutorial shows you how to use nested destructuring in JavaScript. {{outline}} Using Nested Destructuring …