main.js

// Numbers and keys block
const num1 = document.getElementById('num1').value;
const num2 = document.getElementById('num2').value;
const num3 = document.getElementById('num3').value;
const num4 = document.getElementById('num4').value;
const num5 = document.getElementById('num5').value;
const num6 = document.getElementById('num6').value;
const num7 = document.getElementById('num7').value;
const num8 = document.getElementById('num8').value;
const num9 = document.getElementById('num9').value;
const num0 = document.getElementById('num0').value;

// Mathematical symbols and key block
const equals = document.getElementById('equals').value;
const plus = document.getElementById('plus').value;
const minus = document.getElementById('minus').value;
const divide = document.getElementById('divbtn').value;
const multiply = document.getElementById('multiply').value;
const curlsbtn = document.getElementById('curlsbtn').value;
const modulus = document.getElementById('perc').value;
const point = document.getElementById('point').value;

let clearBtn = document.getElementById('cbtn');

// Input & Output block
var entry = document.getElementById('entry');

function get(element)
{
  entry.value += element;
  

}

let usr = '';
// logic block
function getAns(element = equals)
{
  usr += entry.value
  entry.value = '';
  
    let ans = eval(usr)
    entry.value += ans;
  
  usr = '';

}

function clearing(element = clearBtn) {
  entry.value = '';
}
function negativate(){
  entry.value[0] = '-';
}