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

Javascript takes dom elements as string only by default. To make mathematical calculation, you need to typecast it to integer/float or convert to number.

parseInt(number) = number, truncates after decimal value
parseFloat(number) = number with decimal values
Number(number) = number with or without decimal