You can use a built-in function on the Array prototype to join together an array as a string separated by commas in JavaScript.
Introduction: Join Together Array Items as a String
One of JavaScript’s most helpful built-in array methods is .join() (Array.prototype.join()), which returns a string primitive.
“The
join()method creates and returns a new string by concatenating all of the elements in an array (or an array-like object), separated by commas or a specified separator string.” — MDN Docs
You can use any separator you want. In fact, the separator string can be anything at all, of any number of characters.
That means it’s easy to turn your JavaScript array into a comma-separated list format, whether you’d like to add just a comma or a comma and a space. …
Being able to share all props from parent to child component in React lets you easily break your app up into small components. Here’s how to pass all of the React props at the same time.
Passing Props from Parent to Child in React
When you have a React component who received some props (“properties”) from its parent component, and you want to pass all of those props on to this component’s child, then you need to pass the entire props object.
If you happen to know all of the props, then you could pass them all by just listing them out individually as the new props for the child component.
Let’s look at a code example of a ParentComponent that passes all of its props to two child components, DisplayAllProps and ChildComponent. …
Let’s find the distinct values for a given property among all of the JavaScript objects in an array in this short tutorial.
JavaScript Unique Values for a Property in an Array
The ES6 object type Set only accepts one copy of each primitive value added to it, so it’s used to find unique values in JavaScript.
However, it’s not obvious how to use Set to find the unique values for a given property among all of the objects contained in a JavaScript array.
For example, you might have an array of orders from which you’d like to retrieve the unique email addresses of the people who made the orders.
So, for each order, you need to save the email property, but you don’t want any duplicate emails to appear in the list you save. …
A beginner’s guide
When you’re a #CodeNewbie starting out on #100DaysOfCode, your Visual Studio Code setup probably leaves a lot to be desired. Here’s how to go from zero to professional web developer by installing and configuring some crucial extensions, themes, and add-ons.
What separates a professional web developer’s VS Code from a brand-new installation is the use of extensions, especially code formatters and linters that automatically detect and fix problems in your code.
Using code formatters (typically Prettier) and linters (usually ESLint) tend to be mandatory when contributing to open-source projects online. But they’re generally awesome to have even if you never plan to work on open-source. …
Array.isArray([]) vs. Object.prototype.toString.call([])
JavaScript arrays are a type of object, so typeof [] returns "object" — not very helpful to see if you have an array. Here are 5 methods to check whether a JavaScript object is an array.
A common problem in JavaScript data validation is checking to see whether a given variable contains an array.
“Arrays are list-like objects whose prototype has methods to perform traversal and mutation operations.” — MDN Docs
For primitive types, the typeof keyword usually works pretty well, but the typeof an array is "object": typeof [] === object // true.
While that makes sense (arrays are a built-in type of JavaScript object, after-all), it is not useful for differentiating arrays from other objects.
Plus, getting "object" from typeof could indicate a null value. …
Finding the unique strings from a JavaScript array is a common task for web developers — here’s three ways of how to do it.
A Unique Array of Strings
When working with or learning JavaScript, it’s inevitable that you’re going to have to find the unique strings in an array.
It’s a perfect practice problem for learning how to use Set, an ES6 feature, combined with the ... spread operator, as you will see later.
But it’s also a real-life problem. Maybe your React app needs to find a list of all of the unique email addresses for your clientele.
Or maybe you need to get the unique usernames from some type of database you’ve loaded with JSON over an API connection. …
Need unique values in JavaScript? That’s where the Set object comes in. Here’s how to use Set to filter a list of unique primitive values, objects by reference, or objects by their contents (values).
Unique JavaScript Values? Think Set
A Set is a unique collection of items, and it has the advantage over JavaScript objects that you can iterate through the items of a Set in insertion order.
“The
Setobject lets you store unique values of any type, whether primitive values or object references.” — MDN Docs
In other words, you can loop through a Set like an array, and the items stay in the order that they were found in. The properties of a JavaScript object do not retain their insertion order, so the order the properties were added to an object is lost in translation if use try to filter unique items using an object. …
Join Dr. Derek Austin 🥳 weekdays for free JavaScript tutorials at https://twitch.tv/ChillhopAndCode
I’m starting a livestream on Twitch today October 30. It’s called @ChillhopAndCode and will be streaming 1–9pm EDT today and then 12–8pm EST weekdays about programming and web development.
The first segment (1pm EDT / 12pm EST) is Ask Doctor Derek.
https://twitch.tv/ChillhopAndCode
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Windows 10 has a built-in Sticky Notes app that is super useful if, like me, you threw away all your paper while tidying up.
I think I took “paperless” too literally.
There’s no paper in my house, except a Halloween card from my parents, a postcard from some friends, and watercolor paper postcards for my art.
I’m sure Marie Kondo would approve, and I did work hard at the KonMari method to get here… Paper just didn’t “spark joy” in my heart.
There’s only one little problem.
I have nowhere to write anything down!
Whoops.
Why I Use Virtual Sticky Notes
In my case, I managed to get rid of paper because I scanned everything important into a note-taking program, Evernote.
However, Evernote is not great for disposable notes — it’s much better for reference material and scanned items. …
You’ll program faster if you try to make your code simple, even repetitive, when you first write it
Programming is a lot like writing — you should start with a “bad first draft” that solves the problem, then immediately edit it two or three times before you move on to the next problem.
Engineers scoff at being compared to measly “writers” — but who wrote the documentation that you used earlier today? And don’t you “write code?”
Software developers have the luxury of working in the most creative type of engineering. After all, software engineers get to call a lot more shots when building an app than civil engineers do when building a bridge.
Working in a creative profession means that you can learn a great deal from writers whose words will never execute. And one of the best pieces of writing advice is something typically recommended to solve writer’s block. …
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