This is a basic Application which demonstrates how Javascript can calculate values provided by the user.

Users can select to:

  • Add values,
  • Subtract values,
  • Multiply values,
  • Divide values.
Value 1:
Value 2:
Operator:

The result :


The following Javascript code is used:
                
                  function calc() {
                    var a = parseInt(document.querySelector("#value1").value);
                    var b = parseInt(document.querySelector("#value2").value);
                    var op = document.querySelector("#operator").value;
                    var calculate;
                
                    //Check values are numerical
                
                    if(isNaN(a)){
                        alert("You must provide a number for Value 1!");
                    }
                
                    if(isNaN(b)){
                        alert("You must provide a number for Value 2!");
                    }
                
                    if (op == "add") {
                        calculate = a + b;
                    } else if (op == "min") {
                        calculate = a - b;
                    } else if (op == "div") {
                        calculate = a / b;
                    } else if (op == "mul") {
                        calculate = a * b;
                    } 
                
                    document.querySelector("#result").innerHTML = calculate;
                }