const

const = constans a variable that can't be changed

Enter the radius of a circle:


const PI = 3.14159;
let radius;
let circ;

document.getElementById("button_submit").onclick = function () {
  radius = document.getElementById("input_radius").value;
  radius = Number(radius);
  circ = 2 * PI * radius;
  document.getElementById("p_result").innerHTML = "Obwód wynosi: " + circ;
};