Benchmark: indexOf !== -1 vs > -1

Script Preparation code:

const samples = 1000;
let arr = [];
for (let i = 0; i < samples; i++) {
  arr.push(1);
}

Tests:

indexOf !== -1
for (let i = 0; i < samples; i++) { arr.indexOf(arr[i]) !== -1 }
indexOf > -1
for (let i = 0; i < samples; i++) { arr.indexOf(arr[i]) > -1 }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
indexOf !== -1
indexOf > -1

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; rv:135.0) Gecko/20100101 Firefox/135.0

Browser/OS: Firefox 135 on Windows

View result in a separate tab

Test name	Executions per second
indexOf !== -1	28125.0 Ops/sec
indexOf > -1	25594.8 Ops/sec

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

LLMs can make mistakes. Check important info.

The benchmark presented compares two approaches for testing the presence of an element within an array using the `indexOf` method in JavaScript. Specifically, it evaluates the performance difference between using the expression `arr.indexOf(arr[i]) !== -1` and `arr.indexOf(arr[i]) > -1`. Both expressions aim to determine if the element at index `i` exists in the array `arr`.

### Options Compared

1. **`indexOf !== -1`** 
   - This test case checks whether the result of `indexOf` is not equal to `-1`. In JavaScript, `indexOf` returns the first index of the element if it exists in the array, or `-1` if it does not.

2. **`indexOf > -1`** 
   - This test case evaluates if the result of `indexOf` is greater than `-1`. The logic is effectively the same as the previous one, since `indexOf` returns greater than `-1` if the element is found in the array.

### Pros and Cons

- **Performance**: 
   - The benchmark results indicate a slight variation in performance between the two methods on the evaluated browser (Firefox 135). The `indexOf !== -1` condition executed around **28,125 times per second**, while `indexOf > -1` executed approximately **25,595 times per second**.
   - Depending on the JavaScript engine and optimization techniques, one version may outperform the other, though the performance differences are generally negligible for small-scale applications.

- **Readability**:
   - Both expressions are quite readable. However, `!==` might be preferred by some developers due to its explicitness in indicating that you are checking for strict inequality, which might improve code clarity.

- **Consistency**:
   - Although they are functionally equivalent, subtle differences in how they are perceived by developers and how they might be optimized by the JavaScript engine could lead to different preferences in coding styles across teams and projects.

### Other Considerations

- **Browser Compatibility**: 
   - Both expressions use the standard `indexOf` method, which is widely supported across all modern browsers. However, it's always essential to ensure compatibility with the specific environment in which your application runs.

- **Input Size**:
   - As array size increases, the relative performance impact of the approach used may become more significant. It's essential to conduct benchmarks relevant to the anticipated input sizes.

### Alternatives

1. **Using `Array.includes()`**:
   - A modern alternative to `indexOf` is `arr.includes(arr[i])`. This method returns a boolean indicating whether the array contains the specified element. It is more straightforward and directly expresses the intent without needing to compare indices.

2. **Using a Set**:
   - If you frequently check for the existence of elements in a large dataset, consider using a `Set`. Sets provide O(1) average time complexity for lookups. You could initialize a `Set` with the array values and use the `has` method to check for presence: `mySet.has(arr[i])`.

3. **Using `find()` or `filter()`**:
   - If you need more complex conditions, methods like `arr.find()` or `arr.filter()` provide greater flexibility but could be less performant than `indexOf` for simple existence checks.

In conclusion, the benchmark illustrates a comparative analysis of two similar methods for checking element presence in arrays, emphasizing the need for awareness of both performance metrics and coding practices when choosing among them.

Related benchmarks:

indexOf !== -1 vs > -1 (version: 1)

Comparing performance of: indexOf !== -1 vs indexOf > -1

Created: one year ago by: Guest

Jump to the latest result

indexOf !== -1

indexOf > -1

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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