calculate with javascript code example

Example 1: calculate two number and diplay next field without reload the page javascript

var text1 = document.getElementById("Text1");
var text2 = document.getElementById("Text2");

function add_number() {
   var first_number = parseFloat(text1.value);
   if (isNaN(first_number)) first_number = 0;
   var second_number = parseFloat(text2.value);
   if (isNaN(second_number)) second_number = 0;
   var result = first_number + second_number;
   document.getElementById("txtresult").value = result;
}

Example 2: js calculate

answer_Add = 5 + 1; //answer = 6
answer_Sub = 5 - 1; //answer = 4
answer_Multi = 5 * 5; //answer = 25
answer_Divi = 10 / 2; //answer = 5
Total = answer_Add + answer_Sub + answer_Multi + answer_Divi;