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Lesson Content

Build a Calculator 🧮

Create a functional calculator that handles basic math operations. Great for learning JavaScript logic!

Calculator Logic

let currentValue = 0;
let operator = null;
let previousValue = 0;

function calculate(a, op, b) {
  switch(op) {
    case '+': return a + b;
    case '-': return a - b;
    case '*': return a * b;
    case '/': return a / b;
    default: return b;
  }
}

function handleOperation(op) {
  if (operator) {
    currentValue = calculate(previousValue, operator, currentValue);
  }
  operator = op;
  previousValue = currentValue;
  currentValue = 0;
}

Example Code

Build calculator logic

function calculate(a, op, b) {
  switch(op) {
    case '+': return a + b;
    case '-': return a - b;
    case '*': return a * b;
    case '/': return b !== 0 ? a / b : 'Error';
    default: return b;
  }
}

function performCalculation() {
  return calculate(10, '+', 5);
}

console.log('Result:', performCalculation());

Expected Output:

Result: 15

Study Tips

•Read the theory content thoroughly before practicing
•Review the example code to understand key concepts
•Proceed to the Practice tab when you're ready to code