Benchmark: Date.now() vs Math.random()

HTML Preparation code:

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Script Preparation code:

/*your preparation JavaScript code goes here
To execute async code during the script preparation, wrap it as function globalMeasureThatScriptPrepareFunction, example:*/
async function globalMeasureThatScriptPrepareFunction() {
    // This function is optional, feel free to remove it.
    // await someThing();
}

Tests:

Date.now()
Date.now()
Math.random()
Math.random()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Date.now()
Math.random()

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36

Browser/OS: Chrome 142 on Windows

View result in a separate tab

Test name	Executions per second
Date.now()	13082514.0 Ops/sec
Math.random()	36935464.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 6 months ago):

LLMs can make mistakes. Check important info.

The benchmark outlined in the provided JSON compares the performance of two JavaScript functions: `Date.now()` and `Math.random()`. Here's a detailed explanation of the benchmark, the functions being tested, potential pros and cons of each approach, and alternative methods.

### Benchmark Overview

- **Tests Conducted**: 
  - **Date.now()**: This function returns the number of milliseconds elapsed since January 1, 1970, 00:00:00 UTC.
  - **Math.random()**: This function generates and returns a pseudo-random floating-point number between 0 (inclusive) and 1 (exclusive).

### Performance Insights

- **Test Results**: 
  - The benchmark results indicate that `Math.random()` achieved approximately **84,222,032 executions per second**, while `Date.now()` had about **25,769,990 executions per second**.
  - This suggests that calling `Math.random()` is significantly faster than `Date.now()` in the tested environment.

### Pros and Cons of Each Approach

#### 1. **Date.now()**
   - **Pros**:
     - Simple and straightforward for measuring time.
     - Very useful for timestamping events or measuring elapsed time.
   - **Cons**:
     - Performance can be affected by system clock resolution and overhead from converting the system time.
     - Not suitable for generating random numbers.

#### 2. **Math.random()**
   - **Pros**:
     - Fast and efficient for generating random numbers, making it useful for many applications including games, simulations, and random sampling.
     - It is designed to be quick, optimizing for speed in generating random values.
   - **Cons**:
     - The randomness is pseudo-random, meaning it is predictable if the algorithm's seed is known, which might not be suitable for cryptographic purposes.
     - May not be sufficient for applications requiring high quality randomness, like secure key generation.

### Other Considerations

- **Use Cases**:
  - Choose `Date.now()` when the purpose is to track time accurately and not for performance-critical repeated operations.
  - Use `Math.random()` when numerous random values are needed rapidly, such as in random number generation for games or sampling.

### Alternatives

- **For Date/Time Measurements**:
  - Use the `performance.now()` method, which provides a more precise timestamp with sub-millisecond accuracy. This is particularly useful when measuring time intervals for performance testing.
  
  ```javascript
  let start = performance.now();
  // operation to measure
  let end = performance.now();
  console.log(`Operation took ${end - start} ms`);
  ```

- **For Random Number Generation**:
  - If more robust randomness is needed (especially for cryptographic use), the Web Crypto API can be employed with `crypto.getRandomValues()`, providing cryptographically secure random values.
  
  ```javascript
  let array = new Uint32Array(1);
  window.crypto.getRandomValues(array);
  let randomValue = array[0] / (0xffffffff + 1); // normalize to [0, 1)
  ```

By understanding the characteristics and performance implications of `Date.now()` and `Math.random()`, developers can make informed decisions when selecting which method to use based on their application's requirements.

Related benchmarks:

Date.now() vs Math.random() (version: 1)

Comparing performance of: Date.now() vs Math.random()

Created: 6 months ago by: Guest

Jump to the latest result

Date.now()

Math.random()

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 6 months ago):