This benchmark measures the performance of different approaches for extracting date components (day, month, and year) from a date string dateStr formatted as "2021-08-10". The goal is to compare the speed of different JavaScript methods employed for string manipulation—specifically, the split, slice, substring, and the Date.toLocaleString method for extracting and formatting date components.

Options Compared

1. String.split() Method

   • Code: const [yyyy, mm, dd] = dateStr.split("/");
   • Test Name: "split"
   • Description: This method splits the date string into an array using the / character as the delimiter. It is meant for strings formatted with slashes.

2. Date.toLocaleString() Method

   • Code: const result = new Date(dateStr).toLocaleString("pt-PT");
   • Test Name: "Date toLocaleString"
   • Description: This method converts a date object to a localized string representation, in this case, formatted according to Portuguese conventions. It is not directly extracting the components but rather converting the date into a specific string format.

3. String.slice() Method

   • Code: const day = dateStr.slice(8, 10); ...
   • Test Name: "slice"
   • Description: This method extracts a section of the string based on specified start and end indices. It is straightforward for fixed-format strings.

4. String.substring() Method

   • Code: const day = dateStr.substring(8, 10); ...
   • Test Name: "substring"
   • Description: Similar to slice, this method extracts characters from a string between two specified indices. The main difference is how the parameters are treated - substring(start, end) does not support negative indices.

Performance Results

The benchmark results indicate the number of executions per second for each method tested:

• substring: 59,513,728.0 executions/second (fastest)
• slice: 57,741,608.0 executions/second (very close to substring)
• split: 9,273,335.0 executions/second (significantly slower)
• Date.toLocaleString: 226,367.15625 executions/second (much slower)

Pros/Cons of Each Approach

1. split()

   • Pros: Simple to use for splitting a string by a delimiter; easy to read.
   • Cons: Slower than other methods when working with fixed-position strings; requires knowledge of the format being split.

2. toLocaleString()

   • Pros: Automatically formats dates according to locale conventions; useful for localized output.
   • Cons: Not efficient for just extracting components; depends on date object conversion; overall performance is the slowest among the tested methods.

3. slice()

   • Pros: Clear and efficient way to extract substrings based on known indices; handles fixed formats well.
   • Cons: If the format changes, it requires adjustments to indices.

4. substring()

   • Pros: Similar to slice; easy to understand and implement; also handles fixed formats efficiently.
   • Cons: May lead to confusion due to its treatment of parameters (no negative indices).

Other Considerations

• Error Handling: All methods might fail or generate incorrect values if the date format does not strictly conform to the expected pattern, which is a significant consideration in real-world applications.
• Flexibility: While methods like split() allow for more dynamic handling of various formats, the performance cost may not be justified for fixed formats.
• Choice of Method: The best method often depends on specific use cases including the need for localization, error handling, and performance requirements.

Alternatives

• Regular Expressions: Another alternative for parsing strings, allowing for more flexible date formats but at a potential cost in performance and readability.
• Libraries: Libraries like Moment.js or date-fns could be employed to handle date parsing and formatting robustly, but they may add additional overhead in terms of bundle size and complexity if only simple operations are required.

In conclusion, the benchmark demonstrates different ways to extract date components, with the slice and substring methods proving to be the most efficient for fixed-format strings, while split and toLocaleString have more specific use cases at a performance cost.