What is this error with JavaScript

Question

How can JavaScript consider addition in it ?!
https://code.sololearn.com/W3z8Rwe40oSK/?ref=app

Answer 1

Do this too:
var x=prompt("Enter the first Number");
var y=prompt("Enter the second Number");
document.write((+x + +y)+"<br>");
document.write(x*y)

Answer 2

the problem is with line
document.write(x+y+"<br>");

because x and y are working as a string

try this 👇👇👇
x=parseInt(x);
y=parseInt(y);
and then
document.write((x+y)+"<br>");

Answer 3

The + infront of the string is equivalent to the parseInt

Answer 4

@Mr. Programmer it says "parselnt" is not defined