Which is faster == or === JavaScript?

Table of Contents

• Introduction
• Performance Comparison: == vs ===
  • 1. Loose Equality (==)
  • 2. Strict Equality (===)
• Practical Example
  • Expected Results
• Conclusion

Introduction

When programming in JavaScript, developers often face the decision of whether to use the loose equality operator (==) or the strict equality operator (===). While both operators serve the purpose of comparing values, their performance and behavior differ significantly. Understanding which operator is faster can help developers write more efficient code.

Performance Comparison: == vs ===

1. Loose Equality (==)

• Type Coercion: The == operator allows for type coercion, meaning JavaScript will attempt to convert the operands to the same type before comparing them. This additional step of type conversion adds some overhead to the execution time.
• Performance: Due to the type coercion process, == tends to be slower than === since it involves more complex logic. The engine needs to determine if coercion is necessary, which can introduce additional processing time.

2. Strict Equality (===)

• No Type Coercion: The === operator compares both value and type directly without any type conversion. This makes the comparison straightforward and less computationally intensive.
• Performance: As a result, === is generally faster than == because it requires less processing. The JavaScript engine can directly compare the values and types without performing additional operations.

Practical Example

Here's a simple benchmark to illustrate the difference in performance between == and ===:

Expected Results

Typically, you will find that the execution time for the strict equality check (===) is shorter than that of the loose equality check (==) due to the reasons mentioned above.

Conclusion

In terms of performance, the strict equality operator (===) is generally faster than the loose equality operator (==) in JavaScript. The primary reason is that === avoids the overhead of type coercion, allowing for quicker comparisons. While performance may not always be the most critical factor, using === is also considered a best practice for code clarity and predictability. By adopting strict equality comparisons, developers can enhance both the efficiency and maintainability of their JavaScript code.