Benchmark: .length vs var with repeats

Tests:

accessing .length
var p = new Array(1000000000) console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length); console.log(p.length);
storing and accessing variable
var p = new Array(1000000000) var l = p.length; console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l); console.log(l);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
accessing .length
storing and accessing variable

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

Let's dive into the Benchmark Definition and test cases.

**What is being tested?**

The benchmark measures the performance difference between two approaches:

1. Accessing `p.length` directly on the array object (`"accessing .length"`).
2. Storing the length of an array in a variable (`"storing and accessing variable"`).

In other words, the test case checks how fast it is to access the `length` property of an array using two different methods: by calling it directly on the array object or by storing its value in a separate variable.

**Options compared**

The two approaches are being tested:

1. **Direct Access**: `p.length`
2. **Storing and Accessing**: Store the length in a variable (`var l = p.length`) and then access it again (`console.log(l)`).

**Pros and Cons of each approach:**

* **Direct Access**:
	+ Pros:
		- Simple and straightforward
		- Likely to be faster since it avoids extra memory allocation and comparison
	+ Cons:
		- May require an extra memory allocation for the variable (in this case, a single number)
		- Could lead to higher memory usage if repeated multiple times
* **Storing and Accessing**:
	+ Pros:
		- Can avoid re-computation of `length` by storing its value in a variable
		- Might be faster since it avoids the extra computation of `p.length` again
	+ Cons:
		- Requires an additional memory allocation for the variable (in this case, a single number)
		- May lead to higher memory usage if repeated multiple times

**Library and its purpose**

The test case uses no external libraries. However, it does rely on the built-in `Array` object in JavaScript.

**Special JS feature or syntax**

There are no special features or syntax used in this benchmark. The tests only use basic JavaScript features like arrays, variables, console logging, and arithmetic operations.

**Alternatives**

Other alternatives for measuring performance differences between accessing an array's length using different methods might include:

1. Using a library like `microbenchmark` (which is actually the website you mentioned: MeasureThat.net) to create more complex benchmarks.
2. Implementing a custom micro-benchmarking framework to optimize test case execution and output.
3. Using a testing framework that includes built-in support for performance benchmarking, such as Jest or Mocha.

These alternatives might provide more advanced features like handling multiple test cases, parallel execution, or more accurate measurement tools. However, the basic approach of comparing two simple methods (Direct Access vs Storing and Accessing) is straightforward and easy to understand.

Related benchmarks:

.length vs var with repeats (version: 0)

Comparing performance of: accessing .length vs storing and accessing variable

Created: 5 years ago by: Guest

Jump to the latest result

accessing .length

storing and accessing variable

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):