js-calculator/script.js at main · SHADw9/js-calculator · GitHub

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const display = document.getElementById('display');

// Append numbers/operators to the screen
function appendValue(value) {
  if (display.value === '0' || display.value === 'Error') {
    display.value = value;
  } else {
    display.value += value;
  }
}

// Clear screen back to 0
function clearDisplay() {
  display.value = '0';
}

// Remove the last character entered
function deleteLast() {
  if (display.value.length === 1 || display.value === 'Error') {
    display.value = '0';
  } else {
    display.value = display.value.slice(0, -1);
  }
}

// Evaluate string calculation using Function constructor (safer alternative to eval)
function calculate() {
  try {
    display.value = new Function(`return ${display.value}`)();
  } catch (error) {
    display.value = 'Error';
  }
}

// 1. Existing calculator functions from before
function appendValue(value) {
  if (display.value === '0' || display.value === 'Error') {
    display.value = value;
  } else {
    display.value += value;
  }
}

function clearDisplay() {
  display.value = '0';
}

function deleteLast() {
  if (display.value.length === 1 || display.value === 'Error') {
    display.value = '0';
  } else {
    display.value = display.value.slice(0, -1);
  }
}

function calculate() {
  try {
    display.value = new Function(`return ${display.value}`)();
  } catch (error) {
    display.value = 'Error';
  }
}

// 2. NEW: Listen for physical keyboard events
window.addEventListener('keydown', (event) => {
  const key = event.key;

  // Numbers (0-9) and Decimal (.)
  if ((key >= '0' && key <= '9') || key === '.') {
    appendValue(key);
  }

  // Operators (+, -, *, /)
  if (['+', '-', '*', '/'].includes(key)) {
    appendValue(key);
  }

  // Equals (Enter or '=')
  if (key === 'Enter' || key === '=') {
    event.preventDefault(); // Prevents default form submission if wrapped in a form
    calculate();
  }

  // Delete / Backspace
  if (key === 'Backspace') {
    deleteLast();
  }

  // Clear (Escape key or 'c' / 'C')
  if (key === 'Escape' || key.toLowerCase() === 'c') {
    clearDisplay();
  }
});