Benchmark: Date.now() vs static now() function

Script Preparation code:

var timestamp = null;
var _timer = 1000000;

function now() {
  if (_timer !== undefined) {
    return _timer;
  }
  _timer = 1000000;
  return _timer;
}

Tests:

Date.now()
timestamp = Math.floor(Date.now() / 1000);
new Date().getTime();
timestamp = now();

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: 2 years ago)

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 16_1_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.1 Mobile/15E148 Safari/604.1

Browser/OS: Mobile Safari 16 on iOS 16.1.1

View result in a separate tab

Test name	Executions per second
Date.now()	2555809.2 Ops/sec
new Date().getTime();	2620918.0 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 JSON and explain what is being tested, compared, and considered in the benchmark.

**Benchmark Definition**

The benchmark definition consists of two test cases:

1. `timestamp = Math.floor(Date.now() / 1000);`
2. `timestamp = now();`

Here, we have two functions to get the current timestamp: `Date.now()` and a custom function `now()`. The goal is to compare their performance.

**`Date.now()`**

`Date.now()` returns the number of milliseconds since the Unix Epoch (January 1, 1970, 00:00:00 UTC). This function calls an internal implementation that returns the current time in milliseconds.

Pros:

* High accuracy and precision
* Widely supported across browsers and platforms

Cons:

* May be slower due to the overhead of calling a built-in function
* Can be affected by system clock resolution (e.g., 15-16 ms on some systems)

**`now()` Custom Function**

The `now()` function is defined in the benchmark script:
```javascript
function now() {
  if (_timer !== undefined) {
    return _timer;
  }
  _timer = 1000000;
  return _timer;
}
```
This function uses a simple caching mechanism to store the last timestamp value. If `_timer` is not defined, it sets it to 1 second (1000 ms) and returns that value.

Pros:

* Fast and lightweight, as it doesn't rely on built-in functions
* Can be useful in situations where high accuracy isn't necessary

Cons:

* May lose precision or introduce jitter due to caching
* Requires manual management of the `_timer` variable
* Not widely supported across browsers and platforms

**Library: `Math.floor()`**

In the first test case, `timestamp = Math.floor(Date.now() / 1000);`, the `Math.floor()` function is used to convert the result of `Date.now()` to an integer. This is done to ensure consistency in measurement.

The `Math.floor()` function returns the largest possible integer less than or equal to a given number. In this case, it's used to convert milliseconds to seconds.

**Special JavaScript Feature: None**

There are no special JavaScript features or syntax used in this benchmark.

**Other Alternatives**

If you want to measure the performance of other timestamp functions, consider these alternatives:

* `new Date().getTime()`: Similar to `Date.now()`, but uses the `getTime()` method instead.
* `performance.now()`: Returns the number of milliseconds since the performance measurement started. This function is part of the Web APIs and provides high-resolution timing.
* Custom timestamp functions: You can create your own custom timestamp functions using techniques like caching or interpolation, similar to the `now()` function in this benchmark.

In summary, the benchmark compares the performance of `Date.now()` and a custom `now()` function. While `Date.now()` offers high accuracy and precision, the custom function provides faster execution but at the cost of precision and manual management.

Related benchmarks:

Date.now() vs static now() function (version: 0)

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

Created: 2 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):