Benchmark: Date.now(); vs new Date().getTime();

Tests:

Date.now();
Date.now();
new Date().getTime();
new Date().getTime();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

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

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 10 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36

Browser/OS: Chrome 137 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Date.now();	31086218.0 Ops/sec
new Date().getTime();	26919366.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark definitions, explain what's being tested, and discuss the pros and cons of each approach.

**Benchmark Definition JSON**

The first `benchmark definition` json contains information about a microbenchmark:
```json
{
    "Name": "Date.now(); vs new Date().getTime();",
    "Description": null,
    "Script Preparation Code": null,
    "Html Preparation Code": null
}
```
Here, the benchmark is comparing two JavaScript methods: `Date.now()` and `new Date().getTime()`. These methods are used to get the number of milliseconds since the Unix Epoch (January 1, 1970) for dates.

**Individual Test Cases**

The second json contains two individual test cases:
```json
[
    {
        "Benchmark Definition": "Date.now();",
        "Test Name": "Date.now();"
    },
    {
        "Benchmark Definition": "new Date().getTime();",
        "Test Name": "new Date().getTime();"
    }
]
```
Each test case has a unique `Test Name` and corresponds to one of the methods being compared.

**Pros and Cons**

1. **Using `Date.now()`**
	* Pros:
		+ Faster execution (on most modern browsers)
		+ More consistent results across different JavaScript engines
	* Cons:
		+ Some older browsers might not support it or return incorrect values
		+ May be affected by system clock resolution (not exactly measured by a fixed number of milliseconds since the epoch)
2. **Using `new Date().getTime()`**
	* Pros:
		+ More widely supported across different JavaScript engines and browsers
		+ Less likely to be affected by system clock resolution
	* Cons:
		+ Generally slower execution compared to `Date.now()`
		+ May have slightly less consistent results across different systems

**Library: `Date`**

The `Date` object is a built-in JavaScript library that provides a way to work with dates and times. Its methods, such as `now()` (for older browsers) or `getTime()` (for modern browsers), are used to get the number of milliseconds since the Unix Epoch.

**Special JS Feature: ES6**

The benchmark uses ES6 syntax (`new Date().getTime();`) which is a relatively recent feature in JavaScript. Most modern browsers support ES6, but it's not universally supported across all systems and versions.

**Other Alternatives**

For measuring time intervals or executing code repeatedly, you can also use:

* `performance.now()` (introduced in ECMAScript 5)
* Web Workers
* timers (e.g., `setInterval()`, `setTimeout()`)
* libraries like `Benchmark.js` or `microbenchmark`

Keep in mind that each approach has its own pros and cons, depending on the specific use case. The choice of which one to use depends on your particular requirements, target audience, and performance considerations.

Related benchmarks:

Date.now(); vs new Date().getTime(); (version: 0)

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

Created: 7 years ago by: Guest

Jump to the latest result

Date.now();

new Date().getTime();

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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