Benchmark: Convert Date object to number(+ vs getTime vs Number), and for i vs foreach

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

let e = [];
let d = new Date();
for(let i=0; i<100; i++){
  e.push(new Date(d));
  d.setDate(d.getDate()+1);
}

Tests:

Plus for i
for(let i=0; i<100; i++){ +e[i]; }
getTime() for i
for(let i=0; i<100; i++){ e[i].getTime(); }
Number() for i
for(let i=0; i<100; i++){ Number(e[i].getTime()); }
Plus foreach
for(let i of e){ +i; }
getTime foreach
for(let i of e){ i.getTime(); }
Number foreach
for(let i of e){ Number(i); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Plus for i
getTime() for i
Number() for i
Plus foreach
getTime foreach
Number foreach

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:135.0) Gecko/20100101 Firefox/135.0

Browser/OS: Firefox 135 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
Plus for i	163382.4 Ops/sec
getTime() for i	14842042.0 Ops/sec
Number() for i	1187312.2 Ops/sec
Plus foreach	173020.2 Ops/sec
getTime foreach	2853309.2 Ops/sec
Number foreach	196136.8 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):

LLMs can make mistakes. Check important info.

The benchmark provided compares various methods of converting Date objects to numbers in JavaScript, specifically focusing on three conversion techniques (`+`, `.getTime()`, and `Number()`) used in two different types of loops: a traditional `for` loop and a `for..of` loop.

### Options Compared

1. **Conversion Methods**:
   - **`+` Operator**: This is the unary plus operator that attempts to convert its operand into a number. When applied to a Date object, it will implicitly call the Date's `valueOf()` method which returns the primitive value of a Date object — effectively the timestamp in milliseconds.
   - **`.getTime()` Method**: This method explicitly retrieves the timestamp (the number of milliseconds since January 1, 1970) directly from a Date object.
   - **`Number()` Function**: This function converts the Date object into a number. It calls the `valueOf()` method under the hood to get the timestamp.

2. **Loop Types**:
   - **Traditional `for` Loop**: This loop iterates over the array `e` by index. It is generally more performant for large collections due to lower overhead compared to certain other constructs.
   - **`for..of` Loop**: This is a more modern and cleaner syntax introduced in ES6 that allows iteration over iterable objects like arrays. It abstracts away index management and can be more readable but may carry a slight overhead in some cases.

### Benchmark Test Cases

- **Plus for `i`**: Tests the unary plus operator in a traditional `for` loop.
- **getTime() for `i`**: Tests the `.getTime()` method in a traditional `for` loop.
- **Number() for `i`**: Tests the `Number()` function in a traditional `for` loop.
- **Plus foreach**: Tests the unary plus operator in a `for..of` loop.
- **getTime foreach**: Tests the `.getTime()` method in a `for..of` loop.
- **Number foreach**: Tests the `Number()` function in a `for..of` loop.

### Performance Insights

From the benchmark results, we can conclude the following:

- The **`getTime()` method** performs the best in both loop types. This is likely due to it being a direct method call that returns the numerical representation of the Date object without any additional conversion steps.
- The unary **`+` operator** has decent performance but trails behind `getTime()` in a traditional loop and shows even lower performance in a `for..of` loop.
- The **`Number()` function** is significantly slower than both the `getTime()` method and unary plus operator, particularly in a `for..of` loop, where it exhibits substantial overhead due to its function call nature.
- The performance of the traditional `for` loop is simpler and tends to yield better performance compared to the `for..of` loop for nearly all tested cases, suggesting that if performance is critical, sticking to traditional loop constructs may be advantageous.

### Pros and Cons of Approaches

- **`+` operator**:
  - **Pros**: Shorter syntax, compact.
  - **Cons**: Slightly less clear to some developers who may not be familiar with this usage.

- **`.getTime()`**:
  - **Pros**: Explicitly clear in intent, very efficient for Date to number conversion.
  - **Cons**: May seem verbose compared to unary plus, but this is a minor point.

- **`Number()` Function**:
  - **Pros**: Conceptually clear, but its purpose can be broader than just Date conversion.
  - **Cons**: Slower due to more overhead, less efficient compared to the direct `getTime()` access.

### Alternatives

- Other alternatives for date handling might involve libraries such as **Moment.js** or **date-fns** which provide extensive date manipulation and formatting capabilities, but they may introduce additional overhead beyond simple numeric conversion.
- Using native JavaScript features such as the **Temporal API**, which is a newer standard (still in proposals at the time of this writing), could offer more robust date handling in the future.

In summary, in performance-critical applications, prefer using `.getTime()` in a traditional `for` loop for converting Date objects to numbers.

Related benchmarks:

Convert Date object to number(+ vs getTime vs Number), and for i vs foreach (version: 1)

comparing +, getTime and Number, each comparing for i vs foreach

Comparing performance of: Plus for i vs getTime() for i vs Number() for i vs Plus foreach vs getTime foreach vs Number foreach

Created: one month ago by: Guest

Jump to the latest result

Plus for i

getTime() for i

Number() for i

Plus foreach

getTime foreach

Number foreach

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):