Javascript Fundementals (Part 1)

The Complete JavaScript Course 2025

High-level object-oreinted multi-paradigm programming language

VERSIONS:

ES6 is Modern Javascript (2015)

Values and Variables

• Never use: function. new or name as variables. Prefix with _ or $ to use.
• useCamelCase

Data Types

Every value is either OBJECT or PRIMITIVE

PRIMITIVE DATATYPES:

• Number (floating point numbers)
• Strings (sequence of characters
• Boolean (true / false)
• Undefined (empty value)
• Null (empty value)
• Symbol (ES2015) – Unique cannot be changed
• BigInt – Massive numbers

Javascript has dynamic typing – it automatically assigns data type.

typeof – used to display what data type the variable is.

Declaring variables

var is legacy, use let or const. Use const where possible.

Use let if the variable can change.

Use const if the value of the variable cannot be changed (immutable) (also cannot be empty).

Operators

math (+ – / * x**y), assignment (= += -= *= ++ –), comparison (<> ===)

OPERATOR PRECEDENCE

Precedence	Associativity	Individual operators	Notes
18: grouping	n/a	Grouping (x)	[1]
17: access and call	left-to-right	Member access x.y	[2]
		Optional chaining x?.y
	n/a	Computed member access x[y]	[3]
		new with argument list new x(y)	[4]
		Function call x(y)
		import(x)
16: new	n/a	new without argument list new x
15: postfix operators	n/a	Postfix increment x++	[5]
		Postfix decrement x--
14: prefix operators	n/a	Prefix increment ++x	[6]
		Prefix decrement --x
		Logical NOT !x
		Bitwise NOT ~x
		Unary plus +x
		Unary negation -x
		typeof x
		void x
		delete x	[7]
		await x
13: exponentiation	right-to-left	Exponentiation x ** y	[8]
12: multiplicative operators	left-to-right	Multiplication x * y
		Division x / y
		Remainder x % y
11: additive operators	left-to-right	Addition x + y
		Subtraction x - y
10: bitwise shift	left-to-right	Left shift x << y
		Right shift x >> y
		Unsigned right shift x >>> y
9: relational operators	left-to-right	Less than x < y
		Less than or equal x <= y
		Greater than x > y
		Greater than or equal x >= y
		x in y
		x instanceof y
8: equality operators	left-to-right	Equality x == y
		Inequality x != y
		Strict equality x === y
		Strict inequality x !== y
7: bitwise AND	left-to-right	Bitwise AND x & y
6: bitwise XOR	left-to-right	Bitwise XOR x ^ y
5: bitwise OR	left-to-right	Bitwise OR x | y
4: logical AND	left-to-right	Logical AND x && y
3: logical OR, nullish coalescing	left-to-right	Logical OR x || y
		Nullish coalescing operator x ?? y	[9]
2: assignment and miscellaneous	right-to-left	Assignment x = y	[10]
		Addition assignment x += y
		Subtraction assignment x -= y
		Exponentiation assignment x **= y
		Multiplication assignment x *= y
		Division assignment x /= y
		Remainder assignment x %= y
		Left shift assignment x <<= y
		Right shift assignment x >>= y
		Unsigned right shift assignment x >>>= y
		Bitwise AND assignment x &= y
		Bitwise XOR assignment x ^= y
		Bitwise OR assignment x |= y
		Logical AND assignment x &&= y
		Logical OR assignment x ||= y
		Nullish coalescing assignment x ??= y
	right-to-left	Conditional (ternary) operator x ? y : z	[11]
	right-to-left	Arrow x => y	[12]
	n/a	yield x
		yield* x
		Spread ...x	[13]
1: comma	left-to-right	Comma operator x, y