Benchmark: Lodash.isEqual vs JSON.stringify Equality Comparison for Shallow Array of Strings vs ===

HTML Preparation code:

<script src="https://cdn.jsdelivr.net/npm/lodash@4.17.4/lodash.min.js"></script>

Script Preparation code:

window.foo = ['cat', 'dog', 'bird'];
window.bar = ['cat', 'dog', 'bird'];

Tests:

_.isEqual
_.isEqual(window.foo, window.bar)
JSON.stringify
JSON.stringify(window.foo) === JSON.stringify(window.bar);
===
window.foo === window.bar

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
_.isEqual
JSON.stringify
===

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 12 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
_.isEqual	1760576.8 Ops/sec
JSON.stringify	1289858.4 Ops/sec
===	4129818.2 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 13 days ago):

LLMs can make mistakes. Check important info.

The benchmark you're examining compares three different methods for checking equality between two shallow arrays of strings: `_.isEqual` from the Lodash library, equality using `JSON.stringify`, and strict equality using `===`. Each method has its own advantages and disadvantages.

### 1. **Lodash's `_.isEqual`**
**Understanding**: Lodash is a popular JavaScript utility library that provides various functions for common programming tasks. The `_.isEqual` function specifically checks for deep equality, which means it compares values recursively.

**Pros**:
- **Deep Comparison**: It handles nested structures well and is robust, making it a safer choice when comparing arrays or objects that may contain complex data types.
- **Readability**: The intent is clear to other developers reading the code.

**Cons**:
- **Performance**: Compared to simple equality checks, it's typically slower, especially on large or deeply nested structures, due to its recursive nature.
- **Overhead**: Requires importing the Lodash library, which adds extra weight to the application if only a few utility functions are needed.

### 2. **`JSON.stringify` Equality Check**
**Understanding**: This method converts both arrays to JSON strings and then compares the resulting strings using strict equality (`===`).

**Pros**:
- **Simplicity**: Easy to write and understand; it leverages JSON serialization.
- **Handles Order**: It respects the order of elements when serializing arrays, which is crucial for equality checks.

**Cons**:
- **Performance**: `JSON.stringify` can be slower than direct comparisons, especially for large arrays or complex objects, as it has to traverse the entire structure to convert it to a string.
- **Stringification Limitations**: It does not handle circular references and may produce different string outputs for objects with the same data but different key orders.

### 3. **Strict Equality (`===`)**
**Understanding**: This operator checks whether the two references point to the same instance in memory.

**Pros**:
- **Fastest**: This is generally the fastest equality check since it only compares references, not the contents.
- **Simplicity**: It is straightforward and easy to use.

**Cons**:
- **Reference Check**: It only checks if the arrays are the same reference, meaning it will return false unless both variables point to exactly the same object in memory.
- **Ineffective for Content Comparison**: It does not compare the contents of the arrays; hence, two identical arrays will return false if they are different instances.

### **Results from Benchmarking**
The results indicate performance in terms of executions per second for each method when tested in Safari 18 on macOS.

- `===`: ~11.18 million executions per second
- `_.isEqual`: ~5.63 million executions per second
- `JSON.stringify`: ~4.22 million executions per second

The results strongly demonstrate that the strict equality operator `===` outperforms both Lodash's `_.isEqual` and the `JSON.stringify` method, making it the best choice for performance-critical situations when comparing shallow arrays of primitive types.

### **Other Alternative Approaches**
- **Manual Looping**: For smaller arrays, it might sometimes be efficient to manually iterate through the elements and compare each one individually. This could be an optimized approach if only specific conditions for equality are needed.
- **Using `Array.prototype.every()`**: Another modern JavaScript alternative would be to use methods like `every`, which allows for a functional approach to equality checks. This would be faster than `JSON.stringify` for shallow comparisons.
  
In summary, the choice of method depends on the context: if performance is critical and you are only comparing shallow arrays, use `===`. If you need deep object comparisons, use `_.isEqual`, keeping in mind the performance implications. For simple or temporary needs, `JSON.stringify` offers a quick and easy way to check equality for non-complex data structures.

Related benchmarks:

Lodash.isEqual vs JSON.stringify Equality Comparison for Shallow Array of Strings vs === (version: 1)

Test on isEqual performance

Comparing performance of: _.isEqual vs JSON.stringify vs ===

Created: 13 days ago by: Guest

Jump to the latest result

_.isEqual

JSON.stringify

===

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 13 days ago):