What do Javascript types exist?

In JavaScript, there are six primitive types:

1. Number represents numeric values.

// different representions of value 256:
const num1 = 256; // integer Number
const num2 = 256.00; // float Number
const num3 = 0x100; // hexadecimal Number
const num4 = 2.56e2; // exponential Number

// with methods:
const num5 = Number('256');
const num6 = parseInt('256.123');
const num7 = parseFloat('256.00');

// special values:
const NAN = NaN;
const INFINITY = Infinity; // 1 / 0

// it's also valid syntax:
const oneMillion = 1_000_000;

typeof num1; // 'number'

2. String represents a sequence of characters, or text. Strings can be enclosed in single or double quotes.

const str1 = 'string';
const str2 = `${str1}`;
const str3 = String(true);

typeof str1; // 'string'

3. Boolean represents a logical value, either true or false.

const bool = true;

// all values are false:
const bool1 = false;
const bool2 = !bool;
const bool3 = !!bool1;
const bool4 = Boolean(0);
const bool5 = Boolean('');
const bool6 = Boolean(undefined);
const bool7 = Boolean(null);

typeof bool; // 'boolean'

4. null represents a null value, which indicates an absence of a value or a null reference.

const NULL = null;

typeof NULL; // 'object'

5. undefined represents an undefined value, which indicates that a variable has been declared but has not been assigned a value.

const UNDEFINED = undefined;

typeof UNDEFINED; // 'undefined'

6. Symbol represents a unique, immutable value. Symbols are used as a way to create unique, hidden keys for object properties.

const sym1 = Symbol('key');
const sym2 = Symbol('key');

sym1 !== sym2; // true

typeof sym1; // 'symbol'

In addition to these primitive types, JavaScript also has a number of object types, including arrays, functions, and objects.

const arr = [];
const fn = () => {};
const obj = {};

typeof arr; // 'object'
typeof fn; // 'function'
typeof obj; // 'object'