JavaScript Operators

• Operators perform actions on values.
• Expressions combine values and operators to produce a result.
• They are used for calculations, comparisons, and decisions.

What Are Operators?

• An operator is a symbol that performs an action on values.
• Common actions include adding, comparing, and assigning values.

let total = 10 + 5;

• 10 and 5 are operands.
• + is the operator.
• The result is 15.

Arithmetic Operators

• + adds values.
• - subtracts values.
• * multiplies values.
• / divides values.
• % returns the remainder.
• ** raises a number to a power.
• ++ increases a value by 1.
• -- decreases a value by 1.

let a = 10;
let b = 5;

console.log(a + b); // Addition
console.log(a - b); // Subtraction
console.log(a * b); // Multiplication
console.log(a / b); // Division
console.log(a % b); // Remainder

console.log(2 ** 3); // 8

let count = 5;
count++; // 6
count--; // 5

Assignment Operators

• = assigns a value.
• += adds a value and saves the result.
• -= subtracts a value and saves the result.
• *= multiplies by a value and saves the result.
• /= divides by a value and saves the result.

let score = 100;

• The value 100 is assigned to score.

let points = 50;

points += 10;

console.log(points);

• The output is 60.
• points += 10 is the short form shown below.

points = points + 10;

Comparison Operators

• Comparison operators return true or false.
• === checks equal value and equal type.
• !== checks that values or types are different.
• > and < compare greater and smaller values.
• >= and <= include equality in the comparison.

let age = 18;

console.log(age >= 18);

• The output is true.

Logical Operators

• && returns true when both conditions are true.
• || returns true when at least one condition is true.
• ! changes true to false or false to true.
• ?? returns the right value when the left value is null or undefined.

let age = 25;
let hasLicense = true;

console.log(age >= 18 && hasLicense);

• The output is true because both conditions are true.

let nickname = null;

console.log(nickname ?? "Guest"); // Guest

String Operators

• + joins strings.
• += adds text to an existing string.

let fullName = "Asha" + " " + "Kumar";
let message = "Hello";
message += " World";

Conditional Operator

• ? : is also called the ternary operator.
• It returns one value when a condition is true and another when false.

let age = 20;
let status = age >= 18 ? "Adult" : "Minor";

Type Operator

• typeof returns the type of a value.

console.log(typeof 42);      // number
console.log(typeof "Hello"); // string
console.log(typeof true);    // boolean

Optional Chaining

• ?. safely accesses a property or calls a function.
• ?. returns undefined when the value before it is null or undefined.

const user = { profile: { name: "Asha" } };

console.log(user.account?.email); // undefined
user.onLogin?.();

Operator Precedence

• Higher-precedence operators run before lower-precedence operators.
• Multiplication runs before addition.
• Parentheses run first and make the intended order clear.

console.log(2 + 3 * 4);   // 14
console.log((2 + 3) * 4); // 20

Key Takeaways

• Arithmetic operators perform calculations.
• Assignment operators store and update values.
• Comparison and logical operators help make decisions.
• String and ternary operators keep common tasks concise.
• Use parentheses when the order of operations may be unclear.