Benchmark: Date.now() vs +new Date() testing

Script Preparation code:

var timestamp = null;

Tests:

Date.now()
timestamp = Date.now();
+new Date();
timestamp = +new Date();
new Date().getTime()
timestamp = new Date().getTime();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Date.now()
+new Date();
new Date().getTime()

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36 OPR/97.0.0.0

Browser/OS: Opera 97 on Windows

View result in a separate tab

Test name	Executions per second
Date.now()	3739106.5 Ops/sec
+new Date();	2328696.2 Ops/sec
new Date().getTime()	3231404.5 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**What is tested?**

The benchmark tests three different ways to get the current timestamp in JavaScript: `Date.now()`, `+new Date()`, and `new Date().getTime()`.

**Options compared**

1. **`Date.now()`**: This method returns the number of milliseconds since the Unix epoch (January 1, 1970) as an integer.
2. **`+new Date()`**: This method converts a new Date object to its equivalent numerical value, which is the same as `Date.now()`.
3. **`new Date().getTime()`**: This method returns the number of milliseconds since the Unix epoch (January 1, 1970) as an integer, similar to `Date.now()`.

**Pros and Cons**

*   **`Date.now()`**: Pros: simple, efficient, and widely supported across browsers.
    Cons: may not work correctly in older browsers or when used with certain browser extensions that modify the DOM.
*   **`+new Date()`**: Pros: more readable than `Date.now()`, can be useful for debugging purposes.
    Cons: slightly slower than `Date.now()` due to the overhead of parsing a new Date object, and may not work correctly in older browsers.
*   **`new Date().getTime()`**: Pros: equivalent performance to `Date.now()`, more readable than `+new Date()`.
    Cons: similar to `+new Date()`, slightly slower due to the overhead of creating a new Date object.

**Libraries and features**

None of the test cases use any external libraries or special JavaScript features, so there's no additional explanation required for those aspects.

**Other considerations**

*   **Browser differences**: The benchmark results show variations in performance across different browsers (Opera 97). This highlights the importance of testing on multiple platforms to ensure compatibility.
*   **JavaScript engine variations**: The results may also vary depending on the JavaScript engine used by each browser. However, the test cases do not explicitly address these variations.

**Alternative approaches**

Other alternatives for getting the current timestamp include:

1.  **`performance.now()`**: This method is similar to `Date.now()`, but returns the high-precision value of the performance counter, which may be more accurate in certain situations.
2.  **`Intl.DateTimeFormat().resolvedOptions().timeZone`**: This method uses the Internationalized Date and Time Format API to get the current timestamp based on the user's timezone settings.

These alternatives may offer additional benefits or trade-offs, such as improved accuracy or increased complexity, depending on the specific use case.

Related benchmarks:

Date.now() vs +new Date() testing (version: 0)

Comparing performance of: Date.now() vs +new Date(); vs new Date().getTime()

Created: one year ago by: Guest

Jump to the latest result

Date.now()

+new Date();

new Date().getTime()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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