JavaScript for Python Developers

# If/Else
if age >= 18:
    print("Adult")
elif age == 17:
    print("Almost")
else:
    print("Child")

# Iterating a List
for item in items:
    print(item)

/* If/Else */
if (age >= 18) {
  console.log("Adult");
} else if (age === 17) {
  console.log("Almost");
} else {
  console.log("Child");
}

/* Iterating an Array (Note: use 'of', not 'in') */
for (const item of items) {
  console.log(item);
}

import random

def main():
    secret_number = random.randint(1, 100)
    print("Guess the number between 1 and 100!")
    
    while True:
        try:
            guess = int(input("> ").strip())
        except ValueError:
            print("Please type a valid number!")
            continue
            
        if guess < secret_number: 
            print("Higher!")
        elif guess > secret_number: 
            print("Lower!")
        else:
            print("You win!")
            break

if __name__ == "__main__": 
    main()

import * as readline from 'node:readline/promises';
import { stdin as input, stdout as output } from 'node:process';

// JS allows top-level await in modern ES modules!
const rl = readline.createInterface({ input, output });
const secret = Math.floor(Math.random() * 100) + 1;
console.log("Guess the number between 1 and 100!");

while (true) {
    const guessStr = await rl.question('> ');
    const guess = parseInt(guessStr.trim(), 10);
    
    // Number.isNaN is preferred over global isNaN
    if (Number.isNaN(guess)) {
        console.log("Please type a valid number!");
        continue;
    }

    if (guess < secret) console.log("Higher!");
    else if (guess > secret) console.log("Lower!");
    else {
        console.log("You win!");
        break;
    }
}
rl.close();

import random

def main():
    print("Solve the addition problems! Type 'quit' to exit.")
    
    while True:
        a, b = random.randint(1, 10), random.randint(1, 10)
        user_input = input(f"What is {a} + {b}? ").strip()
        
        if user_input == "quit":
            print("Thanks for playing!")
            break
            
        try:
            if int(user_input) == a + b: 
                print("Correct!")
            else: 
                print(f"Wrong! It was {a + b}.")
        except ValueError:
            print("Please enter a number or 'quit'.")

if __name__ == "__main__": main()

import * as readline from 'node:readline/promises';
import { stdin as input, stdout as output } from 'node:process';

const rl = readline.createInterface({ input, output });
console.log("Solve addition! Type 'quit' to exit.");

while (true) {
    const a = Math.floor(Math.random() * 10) + 1;
    const b = Math.floor(Math.random() * 10) + 1;
    
    // JS uses backticks `` for template literals
    const userInput = (await rl.question(`What is ${a} + ${b}? `)).trim();
    if (userInput === 'quit') {
        console.log("Thanks for playing!");
        break;
    }
    
    const answer = parseInt(userInput, 10);
    if (Number.isNaN(answer)) {
        console.log("Enter a number or 'quit'.");
    } else if (answer === (a + b)) {
        console.log("Correct!");
    } else {
        console.log(`Wrong! It was ${a + b}.`);
    }
}
rl.close();

import random
from enum import Enum, auto

class Operation(Enum): ADD = auto(); MULTIPLY = auto()
class AppState(Enum): MENU = auto(); PLAYING = auto(); QUIT = auto()

def main():
    state = AppState.MENU
    op = Operation.ADD

    while state != AppState.QUIT:
        match state:
            case AppState.MENU:
                user_in = input("1. Play  2. Multiply  3. Quit\n> ").strip()
                match user_in:
                    case "1": state = AppState.PLAYING
                    case "2": op = Operation.MULTIPLY
                    case "3": state = AppState.QUIT
                    case _: print("Invalid option.")
            
            case AppState.PLAYING:
                a = random.randint(1, 10)
                b = random.randint(1, 10)
                sym, cor = ("+", a+b) if op == Operation.ADD else ("*", a*b)
                    
                ans = input(f"What is {a} {sym} {b}? ('menu' to exit) ").strip()
                if ans == "menu":
                    state = AppState.MENU
                    continue
                    
                try:
                    if int(ans) == cor: print("Correct!")
                    else: print(f"Wrong, it was {cor}")
                except ValueError: pass

if __name__ == "__main__": main()

import * as readline from 'node:readline/promises';
import { stdin as input, stdout as output } from 'node:process';

const AppState = { MENU: 'MENU', PLAYING: 'PLAYING', QUIT: 'QUIT' };
const Operation = { ADD: 'ADD', MULTIPLY: 'MULTIPLY' };

const rl = readline.createInterface({ input, output });
let state = AppState.MENU;
let op = Operation.ADD;

while (state !== AppState.QUIT) {
    switch (state) {
        case AppState.MENU:
            const menuIn = (await rl.question("1. Play  2. Multiply  3. Quit\n> ")).trim();
            // Don't forget your breaks!
            if (menuIn === "1") state = AppState.PLAYING;
            else if (menuIn === "2") op = Operation.MULTIPLY;
            else if (menuIn === "3") state = AppState.QUIT;
            break; 
            
        case AppState.PLAYING:
            const a = Math.floor(Math.random() * 10) + 1;
            const b = Math.floor(Math.random() * 10) + 1;
            
            // Ternary operators are heavily used in JS
            const symbol = op === Operation.ADD ? '+' : '*';
            const correct = op === Operation.ADD ? a + b : a * b;
            
            const ansStr = (await rl.question(`What is ${a} ${symbol} ${b}? `)).trim();
            if (ansStr === 'menu') { 
                state = AppState.MENU; 
                continue; 
            }
            
            const ans = parseInt(ansStr, 10);
            if (!Number.isNaN(ans)) {
                if (ans === correct) console.log("Correct!");
                else console.log(`Wrong, it was ${correct}`);
            }
            break;
    }
}
rl.close();