Benchmark: array[0] vs array.length > 0 2

Script Preparation code:

var arr = [...Array(1000000).keys()].map((n) => n + 1)

Tests:

array length
if (arr[0]) { console.log(1); } else { console.log(0); }
array length > 0
if (arr.length > 0) { console.log(1); } else { console.log(0); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
array length
array length > 0

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year 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
array length	548279.8 Ops/sec
array length > 0	548079.8 Ops/sec

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

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON compares two different approaches to checking whether an array is non-empty in JavaScript. Specifically, it tests:

1. **Accessing the First Element of the Array (arr[0])**: 
   - **Benchmark Definition**: `if (arr[0]) { console.log(1); } else { console.log(0); }`
   - **Test Name**: "array length"

2. **Checking the Length Property of the Array (arr.length > 0)**:
   - **Benchmark Definition**: `if (arr.length > 0) { console.log(1); } else { console.log(0); }`
   - **Test Name**: "array length > 0"

### Pros and Cons of Each Approach

1. **Using `arr[0]`:**
   - **Pros**:
     - Directly accesses the first element, which may be faster due to fewer property lookups, especially if the array is large.
   - **Cons**:
     - If the array is sparse (i.e., some indices are not set), this would not work as expected if the first element happens to be `undefined`. It implies a need for more context about the state of the array beyond simply being empty.

2. **Using `arr.length > 0`:**
   - **Pros**:
     - This approach is straightforward and reliable for checking whether an array is empty. It does work uniformly regardless of the contents of the array since `length` is a property explicitly defined as the number of elements in the array.
   - **Cons**:
     - It involves accessing the array's length property, which may introduce slight overhead compared to direct element access. However, in modern JavaScript engines, the performance difference may be negligible.

### Other Considerations
- **Performance**: The benchmark provides execution rates, showing that both methods perform at an impressively high rate (over 548,000 executions per second). This suggests that both approaches are efficient, though `arr[0]` may be marginally faster in some environments.
- **Readability**: From a code readability perspective, checking `arr.length > 0` is clearer to a programmer who may not immediately understand the implications of trying to access `arr[0]` on an empty array.

### JavaScript Features
- The benchmarking system uses standard JavaScript features and syntax without employing any special features or syntactical nuances.
- The use of array spread syntax (`[...]`) in the script preparation code to initialize the array demonstrates JavaScript’s capability of easily generating arrays from iterable objects. In this case, it creates an array of integers from 1 to 1,000,000.

### Alternative Approaches
- Other potential methods to check for an empty array might include combining checks (e.g., `(!arr || arr.length === 0)`) to ensure the variable itself is not `null` or `undefined` before checking its length.
- Using helper libraries or `lodash` functions (like `_.isEmpty()`) could provide a more robust and semantic check for emptiness that can accommodate various types of collections, but may introduce additional overhead and dependencies.

In conclusion, both methods provide valid ways to determine if an array is non-empty, with slight performance nuances and different contexts of use in mind.

Related benchmarks:

array[0] vs array.length > 0 2 (version: 1)

Comparing performance of: array length vs array length > 0

Created: one year ago by: Guest

Jump to the latest result

array length

array length > 0

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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