Benchmark: new Date vs date.setTime

Script Preparation code:

var i = 1709062596918;
var prevDate = new Date();

Tests:

new Date
i++; new Date();
date.setTime
i++; prevDate.setTime(i)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Date
date.setTime

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 3 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark that compares two approaches for creating new dates in JavaScript: `new Date()` and `date.setTime()`. The benchmark is designed to measure which approach is faster.

**Options Compared**

Two options are compared:

1. **`new Date()`**: This method creates a new date object by calling the constructor function `Date()`. It returns a `Date` object that represents the number of milliseconds since January 1, 1970, at 00:00:00 UTC.
2. **`date.setTime(i)`**: This method sets the timestamp (in milliseconds) of an existing `Date` object using the value passed as an argument (`i`). It returns the updated `Date` object.

**Pros and Cons**

*   **`new Date()`**:
    *   Pros:
        +   Simpler to implement, as it only requires creating a new object.
        +   May be more efficient for simple use cases where only the timestamp is needed.
    *   Cons:
        +   Creates an entirely new date object, which might incur additional overhead due to object creation and memory allocation.
        +   Requires setting the timestamp using another method (e.g., `date.setTime(i)`), adding extra complexity.
*   **`date.setTime(i)`**:
    *   Pros:
        +   More efficient than creating an entirely new date object, as it modifies an existing one.
        +   Allows for more flexibility in terms of manipulating the timestamp and other properties of the `Date` object.
    *   Cons:
        *   Requires passing a value (`i`) to set the timestamp, which might be more cumbersome than simply creating a new date object.

**Library**

In this benchmark, there is no specific library being used. The tests only involve built-in JavaScript functions and objects (e.g., `Date`).

**Special JS Features or Syntax**

The test case uses incrementing (`i++`) to modify the timestamp value passed to `date.setTime(i)`. This syntax allows for simple incrementing of values.

**Other Considerations**

When designing benchmarks like this, consider the following:

1.  **Test Scope**: Ensure that the benchmark is relevant and representative of real-world scenarios.
2.  **Measurement Resolution**: Choose a suitable measurement resolution (e.g., milliseconds) to capture performance differences accurately.
3.  **Warm-up Periods**: Include warm-up periods or repeated execution cycles to stabilize measurements and avoid false positives.

**Alternative Approaches**

Other alternatives for measuring date creation performance might include:

1.  **`Date.now()`**: Instead of creating a new `Date` object, measure the time it takes to get the current timestamp using this method.
2.  **`Date.parse()`**: Compare the performance of parsing strings into dates versus creating new `Date` objects.

To create more comprehensive benchmarks, consider adding multiple test cases and exploring variations in input values, platform-specific optimizations, or other factors that might affect performance in real-world scenarios.

Latest run results:

Run details: (Test run date: 8 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Windows

View result in a separate tab

Test name	Executions per second
new Date	2695796.0 Ops/sec
date.setTime	5368048.0 Ops/sec

Related benchmarks:

new Date vs date.setTime (version: 0)

Comparing performance of: new Date vs date.setTime

Created: 8 months ago by: Guest

Jump to the latest result

new Date

date.setTime

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 3 days ago):