Benchmark: JS equality vs strict equality

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

let a = undefined;
let b;

const equality = (n) => {
  for (let i = 0; i < n; ++i) {
    b = a == null;
  }
};

const strict_equality = (n) => {
  for (let i = 0; i < n; ++i) {
    b = a === undefined;
  }
};

Tests:

equality
equality(1000000)
strict equality
strict_equality(1000000)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
equality
strict equality

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Windows

View result in a separate tab

Test name	Executions per second
equality	1570.6 Ops/sec
strict equality	1144.3 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The benchmark represented in the provided JSON compares two different methods of checking equality in JavaScript: the loose equality operator (`==`) and the strict equality operator (`===`). Here are the details of what is being tested, the methods compared, their pros and cons, and some considerations around them.

### Benchmark Details

**Benchmark Methods Tested:**
1. **Loose Equality (`==`)**: 
   - In the preparation code, `b = a == null;` checks if `a` is equal to `null`, which can return `true` if `a` is either `null` or `undefined`. This allows for type coercion, meaning it does not require both operands to be of the same type.
  
2. **Strict Equality (`===`)**: 
   - The second method, `b = a === undefined;`, checks if `a` is strictly equal to `undefined`. Here, both the type and value must match, so no type coercion is performed.

Both methods are called within loops that run a million times, allowing for a comparison of how many times each condition can be executed per second.

### Pros and Cons

**Loose Equality (`==`)**:
- **Pros**:
  - More flexible in type comparisons; can handle values that may not be of the same type but are conceptually equal (e.g., `0 == '0'` evaluates to true).
- **Cons**:
  - Can lead to unexpected results due to type coercion (e.g., `[] == false` is true). This behavior can make code harder to reason about and debug, especially for less experienced developers.

**Strict Equality (`===`)**:
- **Pros**:
  - Safer and tends to produce fewer bugs, as it requires both type and value to match. This helps in avoiding unintended type coercion.
- **Cons**:
  - Slightly less flexible; for instance, it will not treat `null` and `undefined` as the same, meaning developers must handle these cases explicitly when necessary.

### Benchmark Results

In the results, we observe the number of executions per second for each method:
- **Loose Equality: 1570.57 executions/second**
- **Strict Equality: 1144.31 executions/second**

This indicates that, in this particular test and on the given browser performance, loose equality is faster than strict equality. However, it's crucial to note that performance results can vary depending on many factors, such as the environment, and should not be the only criterion for choosing one over the other.

### Considerations

- **Real-world Usage**: JavaScript best practices generally recommend using strict equality (`===`) over loose equality (`==`) to avoid bugs related to type coercion. Many team guidelines and style guides enforce this.
  
- **Alternatives**: Alternatives include:
  - **Type-checking Libraries**: Such as `lodash` or `underscore` that offer utility methods for deep equality checks, handling edge cases or nested objects.
  - **Other Scripts/Tools**: Various testing frameworks (e.g., Jest, Mocha) can provide more advanced testing setups for both performance and functional testing.

In summary, the benchmark effectively demonstrates the performance implications and behavior differences between loose and strict equality checks. While loose equality may offer better performance in this isolated test, strict equality is often considered the safer and more reliable approach in production code.

Related benchmarks:

JS equality vs strict equality (version: 3)

Comparing performance of: equality vs strict equality

Created: one year ago by: Registered User

Jump to the latest result

equality

strict equality

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):