Benchmark: Array Access - MeasureThat.net

Script Preparation code:

var touches = [
	{ clientX: 1, clientY: 2},
	{ clientX: 1, clientY: 2}
];

Tests:

no variable
var b = touches[0].clientX; var c = touches[0].clientX;
variable
var a = touches[0]; var b = a.clientX; var c = a.clientX;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
no variable
variable

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
no variable	70258152.0 Ops/sec
variable	73323824.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the provided benchmark definition and test cases.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark that measures the performance of accessing an array element. The benchmark is defined by two scripts:

1. **Script Preparation Code**: This code initializes an array `touches` with two elements, each containing `clientX` properties.
2. **Html Preparation Code**: This field is empty, indicating that no HTML preparation code is required.

The main purpose of this benchmark is to compare the performance of accessing an element in an array by directly accessing its `clientX` property versus accessing it through a variable.

**Options Compared**

There are two test cases:

1. **"no variable"`**: This test case accesses the `clientX` property directly without declaring any variables.
2. **"variable"`**: This test case declares a variable `a` and assigns it to the first element of the `touches` array, then accesses the `clientX` property through this variable.

**Pros and Cons**

### "no variable"

Pros:

* Simplified code: No need to declare an additional variable.
* Reduced overhead: Direct access to the property might be faster since there's no variable lookup.

Cons:

* Potential cache misses: If the array is large or not contiguous in memory, accessing it directly without a variable might result in cache misses, leading to slower performance.

### "variable"

Pros:

* Optimizations: Variable lookups are often optimized by JavaScript engines, reducing overhead.
* Reduced cache misses: Since the variable is declared and stored, there's less chance of cache misses compared to direct access.

Cons:

* Code complexity: Declaring a variable adds complexity to the code.
* Overhead: Looking up variables in memory can introduce additional overhead.

**Library**

There doesn't appear to be any external library used in this benchmark. The performance comparison is based solely on JavaScript's built-in functionality.

**Special JS Feature or Syntax**

This benchmark does not use any special JavaScript features or syntax that would require explanation beyond basic understanding of JavaScript.

**Other Alternatives**

Other approaches to measure array access performance might include:

1. **Using `for...in` loop**: Instead of directly accessing the property, a `for...in` loop could be used to iterate over the array elements.
2. **Using `map()` or `reduce()` methods**: These methods might offer optimized implementations for array iteration and element access.
3. **Measuring individual element access**: This benchmark only tests direct access to an element's property. Measuring individual element accesses, such as `touches[0].clientX`, could provide a more detailed understanding of performance characteristics.

Keep in mind that the specific approach chosen depends on the use case and the desired outcome of the benchmarking process.

Related benchmarks:

Array Access (version: 0)

Comparing performance of: no variable vs variable

Created: 9 years ago by: Guest

Jump to the latest result

no variable

variable

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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