JavaScript

JavaScript is a versatile and widely used programming language that primarily runs on web browsers. It enables interactive and dynamic elements on websites, providing functionalities like validating forms, creating animations, and handling user interactions. JavaScript is also utilized in server-side development, allowing the creation of web applications and APIs. Its syntax is easy to learn and read, making it accessible for beginners. JavaScript’s extensive ecosystem includes libraries and frameworks like React, Angular, and Node.js, empowering developers to build robust and scalable applications. With its cross-platform compatibility and continuous growth, JavaScript has become a fundamental language for both front-end and back-end web development.

How I learned JavaScript

JavaScript was and is confusing to learn, I still struggle with numerous aspects of the language. However, it is essential when it comes to Front End interaction. I have taken and finished a number of FreeCodeCamp courses as part of my self directed study and found The JS Course chalenging and informative. I will likely refer back to it in the future, because it is well structured and available.

FreeCodeCamp Course Description

While HTML and CSS control the content and styling of a page, JavaScript is used to make it interactive. In the JavaScript Algorithm and Data Structures Certification, you’ll learn the fundamentals of JavaScript including variables, arrays, objects, loops, and functions.

Once you have the fundamentals down, you’ll apply that knowledge by creating algorithms to manipulate strings, factorialize numbers, and even calculate the orbit of the International Space Station.

Along the way, you’ll also learn two important programming styles or paradigms: Object Oriented Programming (OOP) and Functional Programming (FP).

Variables

Variables can container many different data types

Declare JavaScript Variables

In computer science, data is anything that is meaningful to the computer. JavaScript provides eight different data types which are undefined, null, boolean, string, symbol, bigint, number, and object.

For example, computers distinguish between numbers, such as the number 12, and strings, such as “12”, “dog”, or “123 cats”, which are collections of characters. Computers can perform mathematical operations on a number, but not on a string.

Variables allow computers to store and manipulate data in a dynamic fashion. They do this by using a “label” to point to the data rather than using the data itself. Any of the eight data types may be stored in a variable.

Variables are similar to the x and y variables you use in mathematics, which means they’re a simple name to represent the data we want to refer to. Computer variables differ from mathematical variables in that they can store different values at different times.

We tell JavaScript to create or declare a variable by putting the keyword var in front of it, like so:

var ourName;

creates a variable called ourName. In JavaScript we end statements with semicolons. Variable names can be made up of numbers, letters, and $ or _, but may not contain spaces or start with a number.

Declaring a sting variable

Variables can be declared in multiple ways.

var myName; var myName = “your name”;

Initializing Variable with the Assignment Operator

var myVar = 0;

Declare String Variables

var myName = “your name”;

Understanding Uninitialized Variables

When JavaScript variables are declared, they have an initial value of undefined. If you do a mathematical operation on an undefined variable your result will be NaN which means “Not a Number”. If you concatenate a string with an undefined variable, you will get a string of undefined.

Camelcase

In camelCase, multi-word variable names have the first word in lowercase and the first letter of each subsequent word is capitalized.

exampleCamelCase anotherExampleOfThis

JS mathematics

The remainder operator % gives the remainder of the division of two numbers.

Example

5 % 2 = 1 because
Math.floor(5 / 2) = 2 (Quotient)
2 * 2 = 4
5 - 4 = 1 (Remainder)

Usage In mathematics, a number can be checked to be even or odd by checking the remainder of the division of the number by 2.

17 % 2 = 1 (17 is Odd)
48 % 2 = 0 (48 is Even)

Note: The remainder operator is sometimes incorrectly referred to as the modulus operator. It is very similar to modulus, but does not work properly with negative numbers.

Golf script

const names = ["Hole-in-one!", "Eagle", "Birdie", "Par", "Bogey", "Double Bogey", "Go Home!"];

function golfScore(par, strokes) {
// Only change code below this line

if (strokes == 1) {
    return names[0];
} else if (strokes <= par - 2) {
    return names[1];
} else if (strokes === par - 1) {
    return names[2];
} else if (strokes === par) {
    return names[3];
} else if (strokes === par + 1) {
    return names[4];
} else if (strokes === par + 2) {
    return names[5];
} else {
    return names[6];
}

// Only change code above this line
}

golfScore(5, 4);