WTF JavaScript tutorial helps newcomers get started with JavaScript quickly.

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All codes and tutorials are open source on github: github.com/WTFAcademy/WTF-Javascript

In this lecture, we will introduce the commonly used data types in JavaScript: numeric value (Number), string (String) and Boolean value (Boolean).

Number is the most commonly used type in JavaScript. It can declare both integers and floating point numbers (decimals).

// declare integer
const int = 10;
// Declare floating point number
const float = 1.1;

There are three special values ​​in JavaScript.

1. NaN: means "not a numeric value", which occurs when an operation that returns a numeric value fails, such as 0 / 0 (meaning 0 divided by 0).

   const nan = 0/0 // NaN

2. Infinity: Infinity, indicating a result that exceeds the upper limit, such as 1 / 0.

   const inf = 1/0 // Infinity

3. -Infinity: negative infinity, indicating a result beyond the lower limit, such as -1 / 0.

   const negInf = -1/0 // -Infinity

Text in JavaScript is represented by the String type. You can mark it with double quotes (""), single quotes (''), or backticks (``).

const str1 = "WTF"; // double quotes (recommended)
const str2 = 'Academy'; // single quote
const str3 = `JavaScript`; // backtick (template string)

In versions after ES6, strings can be marked with backticks, and such strings are called "template literals". It's interesting and can be used for string interpolation: using ${} in a template string allows variables to be inserted into it and parsed.

const name = "0xAA";
const age = 18;
const template = `Name ${name}, age ${age}. `;
console.log(template); // Name 0xAA, age 18.

Changing name and age When the values ​​​​are changed, the template string will also change accordingly.

The Boolean type is used to represent true or false, yes or no. It has only two values: true and false. We often use it in control structures such as if/else statements, which will be covered in later chapters.

const bool1 = true;
const bool2 = false;

Please complete the code below to make it run properly. Note that nickname is a string, age is a numeric value, and isDev is a Boolean value. You can find this code at link.

const nickname = ; // Nickname
const age = ; // age
const isDev = ; // Whether it is a developer
const template = `Welcome ${age} year old ${nickname} to WTF Academy!
Are you a developer? ${isDev}`;
console.log(template);

In this lecture, we introduced the three most commonly used variable types: numeric values, strings, and Boolean values. You will continue to deal with them throughout your JavaScript journey!