Implementing Approximate Number Equality in JavaScript

Introduction

In this lab, we will explore how to implement a function in JavaScript that checks if two numbers are approximately equal to each other. We will use the Math.abs() method to compare the absolute difference between the two values to a specified or default epsilon value. This lab will help us understand how to handle floating-point numbers with precision in JavaScript.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL javascript(("JavaScript")) -.-> javascript/BasicConceptsGroup(["Basic Concepts"]) javascript/BasicConceptsGroup -.-> javascript/variables("Variables") javascript/BasicConceptsGroup -.-> javascript/data_types("Data Types") javascript/BasicConceptsGroup -.-> javascript/arith_ops("Arithmetic Operators") javascript/BasicConceptsGroup -.-> javascript/comp_ops("Comparison Operators") subgraph Lab Skills javascript/variables -.-> lab-28135{{"Approximate Number Equality"}} javascript/data_types -.-> lab-28135{{"Approximate Number Equality"}} javascript/arith_ops -.-> lab-28135{{"Approximate Number Equality"}} javascript/comp_ops -.-> lab-28135{{"Approximate Number Equality"}} end

Checking for Approximate Number Equality in JavaScript

To practice coding, open the Terminal/SSH and type node. This code checks if two numbers are approximately equal to each other. To do this:

Use the Math.abs() method to compare the absolute difference of the two values to epsilon.
If you don't provide a third argument, epsilon, the function will use a default value of 0.001.

Here's the code:

const approximatelyEqual = (v1, v2, epsilon = 0.001) =>
  Math.abs(v1 - v2) < epsilon;

To test the function, you can call it with two numbers as arguments, like this:

approximatelyEqual(Math.PI / 2.0, 1.5708); // true

This will return true because Math.PI / 2.0 is approximately equal to 1.5708 with an epsilon of 0.001.

Summary

Congratulations! You have completed the Approximate Number Equality lab. You can practice more labs in LabEx to improve your skills.