Crafting with JavaScript: Computing with Textiles Software Development Conference QCon New York

in Dec 15, 2021

Beau Carnes will walk you through all of the basic freeCodeCamp JavaScript challenges and provide detailed explanations along the way. Rejecting a promise means ending it with an error (which results in calling the catch() method in whatever uses it). Resolving a promise means to complete it successfully (which results in calling the then() method in whatever uses it). The first is a function we call to resolve the promise, the second a function we call to reject the promise. We first call the function, then we have a then() method that is called when the function ends.

JavaScript Lessons

Template literals are also great because they provide an easy way to interpolate variables and expressions into strings. Another way to define strings is to use template literals, defined inside backticks. They are especially useful to make multiline strings much simpler.

Comparing operands of the same type

This is the reason why regular functions are often used as object methods. Any value that’s not of a primitive type (a string, a number, a boolean, a symbol, null, or undefined) is an object. More advanced expressions involve objects, functions, and arrays, and I’ll introduce them later. Any value that’s not of a primitive type (a string, a number, a boolean, null or undefined) is an object.

  • From the basics to advanced topics with simple, but detailed explanations.
  • A variable is a value assigned to an identifier, so you can reference and use it later in the program.
  • Conditional statements control behavior in JavaScript and determine whether or not pieces of code can run.
  • They are especially useful to make multiline strings much simpler.

Variables are named values and can store any type of JavaScript value. Operators are the symbols between values that allow different operations like addition, subtraction, multiplication, and more. Numbers are values that can be used in mathematical operations.


Though similar in name, the two are very different programming languages. If a variable is defined outside of a function or block, it’s attached to the global object and it has a global scope, which mean it’s available in every part of a program. Everything is as you expect, and how it works in most programming languages. Normally methods are defined on the object instance, not on the class.

  • The challenges are inspired by real-world projects to make sure that you’re learning the best practices, one step at a time.
  • In this article, I will provide a list of free online resources where you can start learning JavaScript.
  • Without complicating your learning process with things that are outside of it, and provided by external ecosystems.
  • My advice is to always use const and only use let when you know you’ll need to reassign a value to that variable.

In particular, it does not mean the value cannot change – it means it cannot be reassigned. If the variable points to an object or an array (we’ll see more about objects and arrays later) the content of the object or the array can freely change. JavaScript is one of the most popular programming languages in the world.

The remainder operator (%)

Typeof is a unary operator that allows us to check the type of a variable. In any moderately complex JavaScript program, everything happens inside functions. I personally prefer single quotes all the time, and use double quotes only in HTML to define attributes. That is called a block, and it is used to group a list of different statements. An if statement is used to make the program take a route, or another, depending on the result of an expression evaluation.

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