Learn what the noop function does and why you'd want to use it. Includes quiz at the end.

JavaScript noop

Learn how to swap variables in JavaScript in two different ways. Includes quiz at the end.

Swap variables in JavaScript: 2 ways to do it

Learn about the possible data types we can and cannot use in JSON. Includes quiz at the end.

JSON data types

Learn about the spread operator and rest parameters. Then test what you learned.

JavaScript three dots (...) in depth

Learn how the operator typeof works.Then test what you learned with interview questions.

JavaScript typeof

Learn how a = b = 2 works in JavaScript. Then test what you learned with interview questions.

JavaScript multiple assignment

Learn how the Boolean function works in JavaScript. Then test what you learned with interview questions.

Boolean function in JavaScript

Learn how !! works in JavaScript. Then test what you learned with interview questions.

JavaScript double bang !! (double negation)

Learn what are truthy values in JavaScript. Test what you learned with interview questions.

Truthy values in JavaScript

Learn what are falsy values in JavaScript. Test what you learned with interview questions.

Falsy values in JavaScript

Learn how to get a random element from an array in Javascript. Test what you learned with interview questions.

Get random element from an array (JavaScript)

Learn how to make the first letter of a string uppercase in JavaScript. Test what you learned with interview questions.

How to capitalize the first letter in JavaScript

Learn how to add elements to an array in JavaScript. Test what you learned with interview questions.

Add element to an array in JavaScript

Find out what is the type of null. Practice what you learned with interview questions.

What is the typeof null in JavaScript

Learn how to remove a property in a JavaScript object. Practice with interview questions.

How to remove a property from a JavaScript object

Learn if a string is inside another string in JavaScript and practice with interview questions.

JavaScript: string contains substring

Learn what is a closure and test your knowledge with interview questions

What is a closure in JavaScript? (with examples)

Learn how to optimize removing an element from an array that is unordered. At the end, you'll have a list of questions to test your knowledge.

Remove item from an array in JavaScript where order doesn't matter

Learn how to remove an element from an array without changing the positions (indexes) of the other elements. At the end, you'll have a list of questions to test your knowledge.

Remove item from an array without changing the indexes in JavaScript

Learn how to remove the first element from an array in multiple ways. At the end, you'll have a list of questions to test your knowledge.

Remove first element from an array in JavaScript

Learn how to remove the last element from an array in multiple ways. At the end, you'll have a list of questions to test your knowledge.

Remove last element from array JavaScript

Learn how to remove the first element found on an array. At the end, you'll have a list of questions to test your knowledge.

JavaScript: Remove element from array

Learn how to remove all items from an array.  You'll see how to do it by mutating or not the original array. At the end, you'll have a list of questions to test your knowledge.

Remove items from array in JavaScript

Learn how Promise.all, Promise.race and Promise.allSettled work. At the end, you'll have a list of questions to test your knowledge.

JavaScript Promise.all, Promise.race and Promise.allSettled

Learn how the methods Promise.resolve and Promise.reject work and how they compare to the resolve and reject functions of the then method. At the end, you'll have a list of questions to test your knowledge.

JavaScript Promise.resolve and Promise.reject

Learn about the different rules and states that affect JavaScript Promises. At the end, you'll have a list of questions to test your knowledge.

JavaScript Promise states and rules

Learn how to handle errors in JavaScript. You'll also learn several gotchas of error handling. At the end, you'll have a list of questions to test your knowledge.

JavaScript Promise error handling with catch and finally

Learn how to chain Promises in JavaScript. At the end, you'll have a list of questions to test your knowledge.

JavaScript Promise chaining

TEST

Learn why you need Promises. Why you need them and how they work. At the end, you'll have a list of questions to test your knowledge.

What is a Promise in JavaScript?

Why even doing minor contributions to open source can be very satisfying.

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