javascript (+) sign concatenates instead of giving sum?

Question

I created a simple program that make the sum of two numbers BUT.. the program is concatenating instead, This is so confusing! Can anyone help?

Answer 1

Use parseInt() for this, Check snippet below

function calculate() {
    var numberOne = document.querySelector(".first").value;
    var numberTwo = document.querySelector(".second").value;
    var sum = parseInt(numberOne) + parseInt(numberTwo);
    document.querySelector(".result").innerHTML = "The sum of the two numbers is : " + sum;
  }

 
Calculate sum of two numbers !
  Enter 1rst Number:

  


  Enter 2nd Number: