How to check two numbers are approximately equal in JavaScript ?

In this article, we are given two numbers and the task is to check whether the given numbers are approximately equal to each other or not. If both numbers are approximately the same then print true otherwise print false.

Example:

Input:  num1 = 10.3
        num2 = 10

Output: true

Approach: To check whether the numbers are approximately the same or not, first, we have to decide the epsilon value. Epsilon is the maximum difference between two numbers, if the difference between the numbers is less than or equal to epsilon then the numbers are approximately equal to each other. So first we create a function named checkApprox which takes three arguments num1, num2, and epsilon. Now check the absolute difference between num1 and num2 is less than epsilon or not.

Example 1: This example shows the above-explained approach.

Javascript

<script>
    const checkApprox = (num1, num2, epsilon) => {

      // Calculating the absolute difference
      // and compare with epsilon
      return Math.abs(num1 - num2) < epsilon;
    }

    console.log(checkApprox(10.003, 10.001, 0.005));
</script>

Output:

true

Example 2: In this example, we will check if the numbers are equal using the Math.abs() method.

Javascript

<script>
    const checkApprox = (num1, num2, epsilon = 0.004) => {
      return Math.abs(num1 - num2) < epsilon;
    }

    console.log(checkApprox(Math.PI / 2.0, 1.5708));
</script>

Output:

true

Example 3: This example checks for the numbers if they are equal or not.

Javascript

<script>
    const checkApprox = (num1, num2, epsilon = 0.004) => {
      return Math.abs(num1 - num2) < epsilon;
    }

    console.log(checkApprox(0.003, 0.03));
</script>

Output:

false