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🔢 JavaScript Operators & Expressions – Complete Guide for Beginners (2025)

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🧲 Introduction – What Are Operators and Expressions?

In JavaScript, operators are special symbols used to perform operations on variables and values. An expression is any valid combination of literals, variables, and operators that returns a result.

🎯 In this guide, you’ll learn:

• Different types of operators in JavaScript
• How expressions are evaluated
• Operator precedence and associativity
• Special operators like typeof, delete, and ...spread

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📘 Topics Covered

🧩 Topic	🔍 Description
JavaScript Operators	Overview of all operator types
Assignment Operators	Assigning values to variables
Arithmetic Operators	Performing math calculations
Comparison Operators	Comparing values
Logical Operators	Handling logical conditions
Bitwise Operators	Binary-level operations
Conditional Operators	Ternary decision-making
typeof Operator	Checking data types
Nullish Coalescing Operator	Handling null and undefined
Safe Assignment Operator	Logical assignment variants
Delete Operator	Removing properties from objects
Comma Operator	Evaluating multiple expressions
Grouping Operator	Controlling operation order
Yield Operator	Pausing functions (Generators)
Spread Operator	Expanding arrays/objects
Exponentiation Operator	Raising to a power (**)
Operator Precedence	Order of operation execution

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🛠️ JavaScript Operators – What Are They?

Operators are used to perform operations on data values. Examples:

let x = 10 + 5; // '+' is an arithmetic operator

✅ Operators return values and form expressions that drive logic and behavior in programs.

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📝 JS Assignment Operators

Assignment operators assign values to variables:

Operator	Example	Equivalent
=	a = b	Assign value of b to a
+=	a += b	a = a + b
-=	a -= b	a = a - b
*=	a *= b	a = a * b
/=	a /= b	a = a / b
%=	a %= b	a = a % b

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➕ JavaScript Arithmetic Operators

Used to perform basic math:

Operator	Description	Example
+	Addition	5 + 3 → 8
-	Subtraction	5 - 3 → 2
*	Multiplication	5 * 3 → 15
/	Division	6 / 2 → 3
%	Modulus	5 % 2 → 1
**	Exponentiation	2 ** 3 → 8
++	Increment	x++
--	Decrement	x--

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⚖️ JavaScript Comparison Operators

Used in condition checking:

Operator	Description	Example
==	Equal (loose)	"5" == 5 → true
===	Strict equal	"5" === 5 → false
!=	Not equal	4 != 5 → true
!==	Strict not equal	"4" !== 4 → true
>	Greater than
<	Less than
>=	Greater than or equal
<=	Less than or equal

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🔗 JavaScript Logical Operators

Used to combine or negate boolean expressions:

Operator	Description	Example
&&	Logical AND	true && false → false
`		`
!	Logical NOT	!true → false

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🧮 JavaScript Bitwise Operators

Operate on binary representations:

Operator	Description
&	AND
`	`
^	XOR
~	NOT
<<	Left shift
>>	Right shift
>>>	Zero-fill right shift

Example:

5 & 1 // 1 (binary: 0101 & 0001 = 0001)

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❓ JavaScript Conditional (Ternary) Operator

The only ternary operator in JS:

let status = age >= 18 ? "Adult" : "Minor";

🧠 Syntax: condition ? expr1 : expr2

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🔍 JavaScript typeof Operator

Returns the type of a value:

typeof "hello" // "string"
typeof 42      // "number"
typeof null    // "object" (JS quirk)

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💡 Nullish Coalescing Operator (??)

Returns the right-hand value if the left is null or undefined:

let name = null ?? "Guest"; // "Guest"

✅ Better than || when 0 or "" should be valid.

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🛡️ Safe Assignment Operators

Logical assignment operators:

Operator	Example	Description
`		=`
&&=	a &&= b	Assign b if a is truthy
??=	a ??= b	Assign b if a is null/undefined

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🗑️ JavaScript delete Operator

Removes object properties:

let obj = { name: "John" };
delete obj.name; // true

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📚 JavaScript Comma Operator

Allows multiple expressions in a single statement:

let x = (1 + 2, 3 + 4); // x = 7

📌 Only the last expression’s value is returned.

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🧮 JavaScript Grouping Operator

Used to control precedence using parentheses:

let result = (2 + 3) * 4; // 20

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🔄 JavaScript yield Operator

Used with Generators to pause and resume functions:

function* gen() {
  yield 1;
  yield 2;
}

Call with .next() to move through values.

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📦 JavaScript Spread Operator (...)

Expands elements from arrays or objects:

let arr = [1, 2];
let newArr = [...arr, 3, 4]; // [1, 2, 3, 4]

let obj = { a: 1 };
let newObj = { ...obj, b: 2 }; // {a:1, b:2}

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🧨 JavaScript Exponentiation Operator (**)

Raises a number to a power:

let power = 2 ** 3; // 8

Same as: Math.pow(2, 3)

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📊 JavaScript Operator Precedence

Determines the order in which operators are evaluated.

Operator	Precedence
()	Highest
**	Right to left
*, /, %	Left to right
+, -	Left to right
<, >, ==, ===	Comparison
&&, `
=, +=, *=	Assignment (lowest)

📌 Use parentheses () to make complex expressions predictable.

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📌 Summary – Recap & Next Steps

JavaScript operators and expressions are the backbone of logical operations and value assignments in any program. Mastering them gives you control over logic, flow, and calculations.

🔍 Key Takeaways:

• Use arithmetic and assignment operators for calculations
• Use typeof, ??, delete, and spread operators wisely
• Understand operator precedence to avoid logic errors

⚙️ Real-World Relevance:
Operators power everything from form validation to conditionals and API response processing. Every JavaScript app uses them heavily.

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❓ FAQs

Q1: What’s the difference between == and ===?

✅ == performs type coercion, while === checks both value and type strictly.

Q2: When should I use ?? instead of ||?

✅ Use ?? when 0, false, or "" should be treated as valid values (i.e., not falsy).

Q3: Can I delete a variable declared with let?

❌ No. delete only works on object properties.

Q4: What does the yield keyword do?

✅ It pauses a generator function and resumes it on demand using .next().

Q5: What is operator associativity?

✅ It defines the direction of execution (left-to-right or right-to-left) when multiple operators have the same precedence.

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