function append(value) {
  document.getElementById("display").value += value;
}

function clearDisplay() {
  document.getElementById("display").value = '';
}

function calculate() {
  try {
    const result = eval(document.getElementById("display").value);
    document.getElementById("display").value = result;
  } catch {
    document.getElementById("display").value = 'Error';
  }
}
{
  "name": "MMRepa Calculator",
  "short_name": "Calculator",
  "start_url": "/calculator.html",
  "display": "standalone",
  "background_color": "#ffffff",
  "theme_color": "#000000",
  "icons": [
    {
      "src": "/icon-192.png",
      "sizes": "192x192",
      "type": "image/png"
    },
    {
      "src": "/icon-512.png",
      "sizes": "512x512",
      "type": "image/png"
    }
  ]
}

function backspace() {
  const display = document.getElementById("display");
  display.value = display.value.slice(0, -1);
}