Creating a JavaScript Function to Subtract Two Numbers

We can use JavaScript to create a function that will subtract two numbers easily. We simply need to use the subtraction operator – in our function. Here is the simple function to subtract two numbers.

function subtractTwoNumbers(number1,number2){
  return number1-number2;
};

And that’s it.

Our simple function called subtractTwoNumbers takes two parameters, the two numbers you want to subtract. The function just subtracts the second number from the first and then returns the result.

Let’s see some examples of this function in use and the output it produces.

function subtractTwoNumbers(number1,number2){
  return number1-number2;
};

console.log(subtractTwoNumbers(2,3));
console.log(subtractTwoNumbers(-2,3));
console.log(subtractTwoNumbers(3,2));
console.log(subtractTwoNumbers(1092,6732));
console.log(subtractTwoNumbers(-22,-3));
console.log(subtractTwoNumbers(10002,0));

#Output
-1
-5
1
-5640
-19
10002

Creating a JavaScript Function to Subtract Two Numbers Using User Input

Below is an example of how we can create a function that will subtract two numbers, and then execute the function when a user clicks on a button we create. We will call the JavaScript function we create using an onclick event that we will attach to the HTML button.

<p>Enter two numbers below. Click Submit to have the subtracted value of the numbers displayed:</p>
<input id="userVal1" type="number" value1="">
<input id="userVal2" type="number" value2="">
<button onclick="subtractNumbers()">Submit</button>
<div id="results"></div>

Below we will write our function. Because the button has the event onclick="subtractNumbers()", the subtractNumbers() function, which we will create below, will run when the button is clicked. The function will subtract the two numbers that the user enters together and display the result. If something other than a number is entered, NaN will be returned.

We will retrieve the numbers the user has entered using the value property.

function subtractNumbers() {
  var num1 = document.getElementById("userVal1").value;
  var num2 = document.getElementById("userVal2").value;
  var total = Number(num1) - Number(num2);
  document.getElementById("results").textContent = total;    
};

The final code and output for this example is below:

Code Output:

Full Code:

<p>Enter two numbers below. Click Submit to have the subtracted value of the numbers displayed:</p>
<input id="userVal1" type="number" value1="">
<input id="userVal2" type="number" value2="">
<button onclick="subtractNumbers()">Submit</button>
<div id="results"></div>

<script>

function subtractNumbers() {
  var num1 = document.getElementById("userVal1").value;
  var num2 = document.getElementById("userVal2").value;
  var total = Number(num1) - Number(num2);
  document.getElementById("results").textContent = total;    
};

</script>

Hopefully this article has been useful in helping you learn how to create a JavaScript function to subtract two numbers.