Day 4: Arithmetic, Comparison & Logical Operators

Daily Objective

Perform calculations, evaluate comparisons, and construct compound conditions.

1. Arithmetic & Assignment

let balance = 100;
balance += 50;  // 150
balance -= 20;  // 130
balance *= 2;   // 260
balance /= 4;   // 65
const remainder = 10 % 3; // 1 (modulo)

2. Comparison: Strict (===) vs Loose (==)

Always use strict equality (===) and strict inequality (!==)!

5 === '5'; // false (checks value AND type)
5 == '5';  // true (loose equality coerces types, dangerous!)

3. Logical Operators

• && (AND): True only if BOTH conditions are true.
• || (OR): True if AT LEAST ONE condition is true.
• ! (NOT): Inverts the boolean value.

const hasLicense = true;
const isAdult = true;
const canDrive = hasLicense && isAdult; // true

Daily Hands-on Practice (70%)

1. Write 5 comparison expressions evaluating combinations of numbers and strings using both == and ===.
2. Construct a compound logical condition testing if a user is eligible for a discount (e.g., student OR age under 25).