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JavaScript Operators

  • This lesson covers different types of operators used in JavaScript.

  • Introduction to Operators in JavaScript

    In JavaScript, operators are symbols that are used to perform operations on values (operands).

    In simple words:

    Operators tell JavaScript what action to perform on data.

    Why Are Operators Important ?

    Operators are used everywhere in JavaScript:

    • Calculations

    • Conditions

    • Decision making

    • Logical checks

    • Comparisons

    Without operators:

    • No calculations

    • No conditions

    • No logic

    • No real programs

    Basic Structure of an Operator Expression

    operand operator operand

    Example:

    10 + 5

    • 10 → operand

    • + → operator

    • 5 → operand

      Types of Operators Covered in This Lesson

      1. Arithmetic Operators

      2. Comparison Operators

      3. Logical Operators

      Arithmetic Operators

      What Are Arithmetic Operators ?

      Arithmetic operators are used to perform mathematical calculations.

      They work with numbers.

      List of Arithmetic Operators

      OperatorNameDescription
      +AdditionAdds values
      -SubtractionSubtracts values
      *MultiplicationMultiplies values
      /DivisionDivides values
      %ModulusReturns remainder
      ++IncrementIncreases value by 1
      --DecrementDecreases value by 1

    Arithmetic and Increment Operators

    Demonstrates basic arithmetic operations and increment/decrement operators 

    // Addition Operator (+)
let a = 10;
let b = 5;
let result = a + b;
console.log(result); // 15


// Subtraction Operator (-)
let a1 = 10;
let b1 = 4;
console.log(a1 - b1); // 6


// Multiplication Operator (*)
let a2 = 5;
let b2 = 3;
console.log(a2 * b2); // 15


// Division Operator (/)
let a3 = 20;
let b3 = 4;
console.log(a3 / b3); // 5


// Modulus Operator (%) - returns remainder
let a4 = 10;
let b4 = 3;
console.log(a4 % b4); // 1


// Post-Increment (x++)
let x = 5;
console.log(x++); // 5 (first prints, then increases)
console.log(x);   // 6


// Pre-Increment (++y)
let y = 5;
console.log(++y); // 6 (first increases, then prints)


// Decrement Operator (--)
let x1 = 5;
x1--;
console.log(x1); // 4

    • Comparison Operators

      What Are Comparison Operators ?

      Comparison operators are used to compare two values.

      They always return a boolean value:

      • true

      • false

        List of Comparison Operators

        OperatorName
        ==Equal to
        ===Strict equal
        !=Not equal
        !==Strict not equal
        >Greater than
        <Less than
        >=Greater than or equal
        <=Less than or equal

      Comparison Operators

      Demonstrates different comparison operators and best practices 

      // Equal to (==) - compares value only
console.log(5 == "5"); // true


// Strict Equal (===) - compares value and type
console.log(5 === "5"); // false


// Not Equal (!=)
console.log(10 != 5); // true


// Strict Not Equal (!==)
console.log(10 !== "10"); // true


// Greater Than (>)
console.log(10 > 5); // true


// Less Than (<)
console.log(3 < 7); // true


// Greater Than or Equal (>=)
console.log(5 >= 5); // true


// Less Than or Equal (<=)
console.log(4 <= 6); // true


// Best Practice:
// Always prefer === and !==
// Avoid using == and !=

      • Reason: Prevents unexpected type conversion bugs.

        Logical Operators

        What Are Logical Operators ?

        Logical operators are used to:

        • Combine conditions

        • Make decisions

        • Control program flow

        They return boolean values.

      Logical Operators

      AND, OR, and NOT operators used for logical conditions. 

      // Logical AND (&&) - true only if both conditions are true
let age = 20;
let hasID = true;
console.log(age >= 18 && hasID); // true


// Logical OR (||) - true if at least one condition is true
let isAdmin = false;
let isUser = true;
console.log(isAdmin || isUser); // true


// Logical NOT (!) - reverses the result
let isLoggedIn = false;
console.log(!isLoggedIn); // true

      • Operator Precedence 

        JavaScript follows priority rules:

        1. Arithmetic

        2. Comparison

        3. Logical

      Understanding Operator Precedence

      Demonstrates how JavaScript evaluates expressions based on operator priority. 

      // Arithmetic > Comparison > Logical

console.log(5 + 5 > 8 && 10 > 3); // true

      • Common Beginner Mistakes

        • Confusing == and ===

        • Forgetting operator precedence

        • Mixing strings and numbers unknowingly

        • Incorrect logical conditions

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