script.js

var input = document.getElementById("display");

//script to detect if enter button is clicked to evaluate the result

input.addEventListener("keyup", function(event) {
 
 // Number 13 is the "Enter" key on the keyboard
 
 if (event.keyCode == 13) {
 
 // Trigger the button element with a click
 
 document.getElementById("equal").click();
 }
});

// Function to calculate the result
function calculate(operation) {
 let result;
 try {
 result = eval(operation); 
 } catch (error) {}

 if ( result === 0 || isFinite(result) && Boolean(result) ) {
 document.getElementById('display').value = result;
 } else {
 document.getElementById('display').value = 'Invalid operation';
 }

}