JS Arithmetic

JavaScript Arithmetic: Operations, Exponentiation, & Precision

Arithmetic operators perform mathematical calculations on numeric operands. JavaScript supports standard arithmetic along with modulo (%), exponentiation (**), unary negation, and increment/decrement operators.

Arithmetic Operations Overview

flowchart LR
    Arith["Arithmetic Operators"] --> Basic["Basic (+, -, *, /)"]
    Arith --> Power["Exponentiation (**)"]
    Arith --> Remainder["Modulo / Remainder (%)"]
    Arith --> IncDec["Increment ++ / Decrement --"]

Arithmetic Operator Reference

Practical Code Example

// Demonstrating arithmetic operators and pre vs post increment

// 1. Basic Arithmetic & Modulo
let a = 15;
let b = 4;

console.log(`Sum: ${a + b}`);          // 19
console.log(`Quotient: ${a / b}`);     // 3.75
console.log(`Remainder (15 % 4): ${a % b}`); // 3
console.log(`Exponentiation (2 ** 10): ${2 ** 10}`); // 1024

// 2. Pre-increment vs Post-increment
let counter1 = 5;
let result1 = counter1++; // Post-increment: assigns 5 to result1, then counter1 becomes 6
console.log(`Post-increment: result1=${result1}, counter1=${counter1}`);

let counter2 = 5;
let result2 = ++counter2; // Pre-increment: counter2 becomes 6, then assigns 6 to result2
console.log(`Pre-increment: result2=${result2}, counter2=${counter2}`);

// 3. Addition Coercion Pitfall
console.log(`Number + Number: ${10 + 20}`);       // 30
console.log(`Number + String: ${10 + "20"}`);     // "1020" (Concatenation!)
console.log(`String - Number: ${"30" - 10}`);     // 20 (Coerced to number!)

Best Practices & Gotchas

• Watch Out for String Addition Coercion: If either operand in a + expression is a string, JavaScript converts the other operand to a string and concatenates them.
• Use Math.floor(a / b) for Integer Division: JavaScript division / returns floating-point numbers.
• Use % 2 === 0 to Check Even Numbers: Modulo % is the standard pattern for checking even/odd parity or array wrap-around indexing.

Self-Check Challenge

What are the final values of x and y after executing let x = 3; let y = x++ + ++x;?