Android/iOS calculator
input.addEventListener("keydown", validateOperator);
function calculate() { const operator = input.value.charAt(input.value.length - 1); const isValid = operators.includes(operator); if (isValid) { return; }
const result = eval(input.value);
input.value = result;
}
function validateOperator(op) {
let value = input.value;
const operator = value.charAt(value.length - 1);
const isValid = operators.includes(operator);
const isValidOp = operators.includes(op.key);
if (isValid && isValidOp) {
input.value = value.substring(0, value.length - 1);
}
}