Benchmark: i++ vs ++i 2 - MeasureThat.net

Tests:

i++
let i = 0; while (i < 1E5) { i++ }
++i
let i = 0; while (i < 1E5) { ++i }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
i++
++i

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
++	19423.1 Ops/sec
+1	19397.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark JSON and explain what's being tested.

**Benchmark Definition**

The test creates two microbenchmarks, "i++" and "++i", which are both measuring the performance difference between incrementing an integer variable using the prefix increment operator (`++`) versus postfix increment operator (`++`).

**Options Compared**

In this benchmark:

* Option 1: `let i = 0; while (i < 1E5) { i++; }`
	+ This option increments the variable `i` directly after the loop condition is evaluated.
* Option 2: `let i = 0; while (i < 1E5) { ++i; }`
	+ This option increments the variable `i` before evaluating the loop condition.

**Pros and Cons**

**Option 1 (`let i = 0; while (i < 1E5) { i++; }`)**

Pros:

* Easier to read and understand, as the increment operation is clearly separated from the loop condition.
* May be more efficient due to compiler optimizations that can reorder the operations.

Cons:

* May not take advantage of the prefix increment operator's ability to increment a register directly, potentially leading to slower performance compared to Option 2.

**Option 2 (`let i = 0; while (i < 1E5) { ++i; }`)**

Pros:

* Can utilize the CPU's ability to increment a register directly, which may result in faster performance.
* May be more efficient for modern CPUs with specialized instructions like `inc` or `add`.

Cons:

* Can be less readable and understandable due to the unclear relationship between the increment operation and the loop condition.

**Library Usage**

There doesn't seem to be any library usage in this benchmark. The code consists of simple JavaScript variables and control structures, making it a native JavaScript performance test.

**Special JS Feature or Syntax**

There are no special JS features or syntaxes mentioned in this benchmark. It only uses standard JavaScript variables and control structures.

**Other Alternatives**

If you wanted to measure the performance difference between `i++` and `++i`, but with additional options, here are some alternatives:

1. **Loop unrolling**: Instead of using a single loop iteration, use multiple iterations with fewer iterations to increase the number of operations.
2. **Variable caching**: Store the result of incrementing `i` in a temporary variable and reuse it instead of re-evaluating the expression in each iteration.
3. **SIMD instructions**: Use SIMD (Single Instruction, Multiple Data) instructions to perform operations on multiple values simultaneously, if available on your target hardware.

Keep in mind that these alternatives may introduce additional complexity and might not be relevant for all use cases or environments.

Overall, the provided benchmark measures the performance difference between two commonly used increment operators in JavaScript. While it's a simple test, understanding the pros and cons of each option can provide valuable insights into optimizing JavaScript code for performance.

Related benchmarks:

i++ vs ++i 2 (version: 1)

Comparing performance of: i++ vs ++i

Created: 2 years ago by: Registered User

Jump to the latest result

i++

++i

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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