What does !== mean in code?

Table of Contents

• Introduction
• Understanding the !== Operator
  • 1. Strict Inequality Comparison
    • Example:
  • 2. No Type Coercion
    • Example:
• Advantages of Using !==
• Conclusion

Introduction

In JavaScript, !== is a strict inequality operator that is used to compare two values to determine if they are not equal. This operator checks both the value and the type of the operands, ensuring that type coercion does not occur during the comparison. This article will explain the significance of the !== operator, how it differs from its loose counterpart, and provide practical examples.

Understanding the !== Operator

1. Strict Inequality Comparison

The !== operator compares two values and returns true if the values are not equal or if their types differ. Unlike the loose inequality operator (!=), which performs type coercion, !== ensures that no automatic type conversion takes place.

Example:

In this example, a is a number, and b is a string. Because their types differ, !== returns true.

2. No Type Coercion

The primary advantage of using !== is that it prevents unexpected behavior due to type coercion. This makes your comparisons more predictable and reliable.

Example:

Here, null and undefined are considered distinct types, so the strict inequality operator returns true, indicating that the values are not equal.

Advantages of Using !==

1. Clarity and Readability: Using !== makes it clear that both value and type are being compared, enhancing the readability of your code.
2. Reduced Risk of Errors: By avoiding type coercion, !== reduces the likelihood of logical errors in your comparisons, leading to fewer bugs.
3. Best Practice: Using strict operators (=== and !==) is generally considered a best practice in JavaScript, as it promotes more predictable code behavior.

Conclusion

The !== operator in JavaScript is a strict inequality operator that checks whether two values are not equal while also considering their types. By using !==, you avoid the pitfalls of type coercion and enhance the clarity and reliability of your code. Adopting this operator as a standard practice will help ensure that your JavaScript applications behave as expected, leading to a better development experience.