Benchmark: push vs index 2020

Script Preparation code:

var a = [];

Tests:

push
for (var j = 0; j<100000; j++) { a.push(i); }
index
for (var j = 0; j<100000; j++) { a[i] = i; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
push
index

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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Let's break down the benchmark and its test cases.

**What is tested?**

The provided benchmark tests two ways of pushing elements to an array in JavaScript: using `a.push(i)` and assigning directly to an index (`a[i] = i`). The benchmark measures which approach is faster, based on the execution time per second (measured as "ExecutionsPerSecond").

**Options compared**

Two options are compared:

1. **`push`**: Using the `push` method to add elements to the end of an array.
2. **Index assignment (`index`)**: Assigning a value directly to an index in the array.

**Pros and Cons**

* **`push`**:
	+ Pros: More concise, easier to read and write, less prone to off-by-one errors (e.g., `a[i] = i;` could lead to skipping some elements).
	+ Cons: May be slower due to dynamic array resizing.
* **Index assignment (`index`)**:
	+ Pros: Can be faster for large arrays since it avoids dynamic array resizing, and can also be more cache-friendly (since the index is fixed).
	+ Cons: More verbose, prone to off-by-one errors (e.g., `i++` instead of `++i`), and less readable.

**Library usage**

There is no explicit library mentioned in the benchmark definition or test cases. However, it's likely that a modern JavaScript engine uses some internal libraries or optimizations that might affect the benchmark results. For example, the `push` method may rely on some internal array management mechanisms that are not visible to the programmer.

**Special JS features or syntax**

There is no mention of special JavaScript features or syntax in the provided code snippet. However, it's worth noting that this benchmark does not test specific modern JavaScript features like `let`, `const`, arrow functions, or async/await, which might be useful for testing performance differences with those features.

**Other alternatives**

In a real-world scenario, you might also consider testing other array manipulation approaches, such as:

* Using an existing library like Lodash's `map` method (`_.map(a, i => i)`).
* Using a stack-based implementation (`var stack = []; while (j < 100000) { stack.push(i); }`).
* Testing with different array sizes or shapes (e.g., arrays of varying lengths or objects).

Keep in mind that the choice of testing approach depends on your specific use case and requirements.

**Additional considerations**

When writing a performance benchmark like this, it's essential to consider factors beyond just code readability:

* **Warm-up**: Make sure to run each test multiple times before measuring its execution time to account for any initial overhead.
* **System variability**: Measure the results across different browsers, devices, and platforms to ensure robustness.
* **Sampling rate**: Choose a sampling rate that balances accuracy with noise reduction (e.g., taking 100-1000 measurements per iteration).
* **Error handling**: Consider implementing error handling mechanisms for unexpected inputs or errors.

By considering these factors and using a well-designed benchmark like this one, you can gain valuable insights into the performance characteristics of your JavaScript code.

Related benchmarks:

push vs index 2020 (version: 0)

Comparing performance of: push vs index

Created: 6 years ago by: Guest

Jump to the latest result

push

index

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):