All the JavaScript Fundamentals tutorials ⤵️
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How to style DOM elements using JavaScript
The ways you can apply styling to elements on the page, dynamically, using plain JavaScript
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Loosely typed vs strongly typed languages
The key differences between using a loosely typed language compared to a strongly typed languages
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Passing undefined to JavaScript Immediately-invoked Function Expressions
Sometimes you can spot old code in the wild where `undefined` is passed to a function. Why?
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Dynamically select a method of an object in JavaScript
Learn how to access a method of an object dynamically in JavaScript
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The TypeScript Guide
TypeScript is one of the fastest rising technologies of 2018. It's everywhere, everyone talks about it. This article guides you towards understanding its key concepts
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The definitive guide to debugging JavaScript
Learn how to debug JavaScript using the browser DevTools debugger
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Destructuring Objects and Arrays in JavaScript
Learn how to use the destructuring syntax to work with arrays and objects in JavaScript
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Work with objects and arrays using Rest and Spread
Learn two modern techniques to work with arrays and objects in JavaScript
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How to count the number of properties in a JavaScript object
Find out how to calculate how many properties has a JavaScript object
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How to sort an array of objects by a property value in JavaScript
Find out how to sort an array of objects by a property value in JavaScript
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How to set default parameter values in JavaScript
Find out how to add a default parameter value into a JavaScript function
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How to encode a URL with JavaScript
You might need to encode a URL if you are sending it as part of a GET request, for example.
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How to empty a JavaScript array
Given a JavaScript array, see how to clear it and empty all its elements
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How to merge two objects in JavaScript
Find out how to merge 2 JavaScript objects and create a new object that combines the properties
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How to hide a DOM element using plain JavaScript
Find out how to hide and then show again elements in vanilla JavaScript
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Should you use or learn jQuery in 2019?
To use or not to use? To learn or not to learn? Let's see how you can avoid jQuery altogether, and the reasons you should keep using it
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The JSONP Guide
JSONP is a way to load data from 3rd party servers, bypassing the same-origin policy
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Introduction to JSON
JSON is a great format to store data, widely used in JavaScript but not only - discover all about it!
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An introduction to WebAssembly
Discover why WebAssembly is a very important part of the Web platform of the future
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What is a Single Page Application?
Modern Web Applications are also called Single Page Applications. What does this mean?
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How to get the index of an iteration in a for-of loop in JavaScript
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HTML Canvas API Tutorial
A guide to the Canvas API, one way offered by browsers to draw to the screen
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How to generate a random number between two numbers in JavaScript
The simplest possible way to randomly pick a number between two
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Async vs sync code
The difference between running code synchronously or asynchronously
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How to remove a file with Node.js
Discover how to remove a file from the filesystem with Node.js
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How to initialize a new array with values in JavaScript
Find out how you can initialize a new array with a set of values in JavaScript
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How to get the current URL in JavaScript
Find out the ways JavaScript offers you to get the current URL that's opened in the browser
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How to create a multiline string in JavaScript
Discover how to create a multiline string
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How to check if a string starts with another in JavaScript
Checking if a string starts with another substring is a common thing to do. See how to perform this check in JavaScript
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How to get the unique properties of a set of objects in a JavaScript array
Given an array of objects, here's what you can do if you want to get the values of a property, but not duplicated.
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How to validate an email address in JavaScript
There are lots of ways to validate an email address. Learn the correct way, and also find out all the options you have, using plain JavaScript
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The JavaScript Cookbook
The JavaScript cookbook contains lots of useful how-to articles that explain how to perform common things in JavaScript
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The JavaScript Arithmetic operators
Performing math operations and calculus is a very common thing to do with any programming language. JavaScript offers several operators to help us work with numbers
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How to inspect a JavaScript object
Find out the ways JavaScript offers you to inspect an object (or any other kind of value)
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How to trim the leading zero in a number in JavaScript
If you have a number with a leading zero, like 010 or 02, how to remove that zero?
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How to replace all occurrences of a string in JavaScript
Find out the proper way to replace all occurrences of a string in plain JavaScript, from regex to other approaches
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How to check if a JavaScript object property is undefined
In a JavaScript program, the correct way to check if an object property is undefined is to use the `typeof` operator. See how you can use it with this simple explanation
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How to append an item to an array in JavaScript
Find out the ways JavaScript offers you to append an item to an array, and the canonical way you should use
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How to remove a property from a JavaScript object
There are various ways to remove a property from a JavaScript object. Find out the alternatives and the suggested solution
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How to redirect to another web page using JavaScript
JavaScript offers many ways to redirect the user to a different web page. Learn the canonical way, and also find out all the options you have, using plain JavaScript
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How to get the current timestamp in JavaScript
Find out the ways JavaScript offers you to generate the current UNIX timestamp
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How to convert a string to a number in JavaScript
Learn how to convert a string to a number using JavaScript
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How to format a number as a currency value in JavaScript
Learn how to convert a number into a currency value, using the JavaScript Internationalization API
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How to uppercase the first letter of a string in JavaScript
JavaScript offers many ways to capitalize a string to make the first character uppercase. Learn the various ways, and also find out which one you should use, using plain JavaScript
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How to deep clone a JavaScript object
JavaScript offers many ways to copy an object, but not all provide deep copy. Learn the most efficient way, and also find out all the options you have
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How to remove an item from an Array in JavaScript
JavaScript offers many ways to remove an item from an array. Learn the canonical way, and also find out all the options you have, using plain JavaScript
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How to check if a string contains a substring in JavaScript
JavaScript offers many ways to check if a string contains a substring. Learn the canonical way, and also find out all the options you have, using plain JavaScript
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Roadmap to Learn JavaScript
JavaScript is such an amazing language! Born as a simple way to manipulate documents in the browser, over the years it became the most popular programming language in the world, and now runs everywhere. Learn the JavaScript Programming Language through simple tutorials following my roadmap
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A list of sample Web App Ideas
Every time I start a tutorial I find myself in a limbo wondering which app should I build. A to-do app? Not again!
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JavaScript Coding Style
This JavaScript Coding Style is the set of conventions I use every day when using JavaScript. It's a live document, with the main set of rules I follow
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How to upload files to the server using JavaScript
Uploading a file an process it in the backend in one of the most common file handling functionalities in a web app
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Deferreds and Promises in JavaScript (+ Ember.js example)
Promises are a relatively new approach to async management, and they can be really helpful to structure your code
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Introduction to the JavaScript Programming Language
JavaScript is one of the most popular programming languages in the world, and now widely used also outside of the browser. The rise of Node.js in the last few years unlocked backend development, once the domain of Java, Ruby, Python, PHP, and more traditional server-side languages. Learn all about it!
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The Complete ECMAScript 2015-2017 Guide
ECMAScript is the standard upon which JavaScript is based, and it's often abbreviated to ES. Discover everything about ECMAScript, and the latest features added in ES6, 7, 8.
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The ES2018 Guide
ECMAScript is the standard upon which JavaScript is based, and it's often abbreviated to ES. Discover everything about ECMAScript, and the features added in ES2018, aka ES9
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The ES2017 Guide
ECMAScript is the standard upon which JavaScript is based, and it's often abbreviated to ES. Discover everything about ECMAScript, and the features added in ES2017, aka ES8
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The ES2016 Guide
ECMAScript is the standard upon which JavaScript is based, and it's often abbreviated to ES. Discover everything about ECMAScript, and the features added in ES2016, aka ES7
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The ES6 Guide
ECMAScript is the standard upon which JavaScript is based, and it's often abbreviated to ES. Discover everything about ECMAScript, and the features added in ES6, aka ES2015.
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The Lexical Structure of JavaScript
A deep dive into the building blocks of JavaScript: unicode, semicolons, white space, case sensitivity, comments, literals, identifiers and reserved words
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JavaScript Variables
A variable is a literal assigned to an identifier, so you can reference and use it later in the program. Learn how to declare one with JavaScript
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JavaScript Types
You might sometimes read that JS is untyped, but that's incorrect. It's true that you can assign all sorts of different types to a variable, but JavaScript has types. In particular, it provides primitive types, and object types.
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JavaScript Expressions
Expressions are units of code that can be evaluated and resolve to a value. Expressions in JS can be divided in categories.
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JavaScript Prototypal Inheritance
JavaScript is quite unique in the popular programming languages landscape because of its usage of prototypal inheritance. Let's find out what that means
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How to use JavaScript Classes
In 2015 the ECMAScript 6 (ES6) standard introduced classes. Learn all about them
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JavaScript Exceptions
When the code runs into an unexpected problem, the JavaScript idiomatic way to handle this situation is through exceptions
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Semicolons in JavaScript
JavaScript semicolons are optional. I personally like avoiding using semicolons in my code, but many people prefer them.
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Quotes in JavaScript
An overview of the quotes allowed in JavaScript and their unique features
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JavaScript Functions
Learn all about functions, from the general overview to the tiny details that will improve how you use them
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A tutorial to JavaScript Arrow Functions
Arrow Functions are one of the most impactful changes in ES6/ES2015, and they are widely used nowadays. They slightly differ from regular functions. Find out how
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JavaScript Closures explained
A gentle introduction to the topic of closures, key to understanding how JavaScript functions work
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JavaScript Arrays, a definitive cheat sheet
JavaScript arrays over time got more and more features, sometimes it's tricky to know when to use some construct vs another. This post aims to explain what you should use, as of 2019
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JavaScript Loops
JavaScript provides many way to iterate through loops. This tutorial explains all the various loop possibilities in modern JavaScript
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JavaScript Events Explained
JavaScript in the browser uses an event-driven programming model. Everything starts by following an event. This is an introduction to JavaScript events and how event handling works
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The JavaScript Event Loop
The Event Loop is one of the most important aspects to understand about JavaScript. This post explains it in simple terms
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JavaScript Asynchronous Programming and Callbacks
JavaScript is synchronous by default, and is single threaded. This means that code cannot create new threads and run in parallel. Find out what asynchronous code means and how it looks like
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Understanding JavaScript Promises
Promises are one way to deal with asynchronous code in JavaScript, without writing too many callbacks in your code.
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A guide to JavaScript Template Literals
Introduced in ES2015, aka ES6, Template Literals offer a new way to declare strings, but also some new interesting constructs which are already widely popular.
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The Set JavaScript Data Structure
A Set data structure allows to add data to a container, a collection of objects or primitive types (strings, numbers or booleans), and you can think of it as a Map where values are used as map keys, with the map value always being a boolean true.
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The Map JavaScript Data Structure
Discover the Map data structure introduced in ES6 to associate data with keys. Before its introduction, people generally used objects as maps, by associating some object or value to a specific key value
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JavaScript Loops and Scope
There is one feature of JavaScript that might cause a few headaches to developers, related to loops and scoping. Learn some tricks about loops and scoping with var and let
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Discover JavaScript Timers
When writing JavaScript code, you might want to delay the execution of a function. Learn how to use setTimeout and setInterval to schedule functions in the future
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call() and apply() in JavaScript
Find out how to use call() and apply() and their difference in JavaScript
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this in JavaScript
`this` is a value that has different values depending on where it's used. Not knowing this tiny detail of JavaScript can cause a lot of headaches, so it's worth taking 5 minutes to learn all the tricks
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JavaScript Strict Mode
Strict Mode is an ES5 feature, and it's a way to make JavaScript behave in a better way. And in a different way, as enabling Strict Mode changes the semantics of the JavaScript language. It's really important to know the main differences between JavaScript code in strict mode, and normal JavaScript, which is often referred as sloppy mode
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JavaScript Immediately-invoked Function Expressions (IIFE)
An Immediately-invoked Function Expression is a way to execute functions immediately, as soon as they are created. IIFEs are very useful because they don't pollute the global object, and they are a simple way to isolate variables declarations
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How to use Async and Await with Array.map()
Using async/await combined with map() can be a little tricky. Find out how.
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Modern Asynchronous JavaScript with Async and Await
Discover the modern approach to asynchronous functions in JavaScript. JavaScript evolved in a very short time from callbacks to Promises, and since ES2017 asynchronous JavaScript is even simpler with the async/await syntax
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The definitive guide to JavaScript Dates
Working with dates in JavaScript can be complicated. Learn all the quirks and how to use them.
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The JavaScript Math object
The Math object contains lots of utilities math-related. This tutorial describes them all
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Introduction to Unicode and UTF-8
Unicode is an industry standard for consistent encoding of written text. Learn the basics and most important parts of it, in particular concerning UTF-8
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Unicode in JavaScript
Learn how to work with Unicode in JavaScript, learn what Emojis are made of, ES6 improvements and some pitfalls of handling Unicode in JS
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An introduction to Functional Programming with JavaScript
Getting started with the main concepts of Functional Programming in the JavaScript Programming Language
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A guide to JavaScript Regular Expressions
Learn everything about JavaScript Regular Expressions with this brief guide that summarizes the most important concepts and shows them off with examples
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Introduction to ES Modules
ES Modules is the ECMAScript standard for working with modules. While Node.js has been using the CommonJS standard since years, the browser never had a module system, as every major decision such as a module system must be first standardized by ECMAScript and then implemented
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Introduction to CommonJS
The CommonJS module specification is the standard used in Node.js for working with modules. Modules are very cool, because they let you encapsulate all sorts of functionality, and expose this functionality to other JavaScript files, as libraries
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The JavaScript Glossary
A guide to a few terms used in frontend development that might be alien to you
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Generate random and unique strings in JavaScript
How I created an array of 5000 unique strings in JavaScript
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A quick reference guide to Modern JavaScript Syntax
Many times, code samples are using the latest JavaScript features available. Sometimes those features can be hard to be distinguished from a framework features. It happens frequently with React for example, which encourages a very modern approach to JavaScript.
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How to make your JavaScript functions sleep
Learn how to make your function sleep for a certain amount of time in JavaScript
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Write JavaScript loops using map, filter, reduce and find
How to perform common operations in JavaScript where you might use loops, using map(), filter(), reduce() and find()