Let's break down the provided benchmarking setup and explain what's being tested, compared, and the pros and cons of each approach.

Benchmark Overview

The benchmark measures the performance difference between two approaches: split() and substr() when extracting date components from a string.

Script Preparation Code

The script preparation code defines an array of dates in the format "dd-mm-yyyy". This is used as input for the benchmarking test cases.

Individual Test Cases

There are two test cases:

1. "Split"`

for(let i=0; i<dates.length; i++) {
  let date = dates[i].split("-"); // split on "-" delimiter
  let dateString = date[2] + "-" + date[1] + "-" + date[0]; // assemble date string
}

This test case uses the split() method to split the date string into an array of substrings, and then uses indexing (date[2], date[1], and date[0]) to extract the individual date components.

2. "Substring"`

for(let i=0; i<dates.length; i++) {
  let dateString = dates[i].substr(6,4) + "-" + dates[i].substr(4,2) + "-" + dates[i].substr(0,2); // extract date components using substr()
}

This test case uses the substr() method to extract specific parts of the date string. The syntax is as follows:

• dates[i].substr(startIndex, length) extracts a substring starting at startIndex with a length of length.

Comparison

The benchmark compares the performance of the two approaches: split() and substr(). The test case with the highest execution rate (in this case, "Split") is considered faster.

Pros and Cons

• "Split"`
  • Pros:
    • Easy to read and understand.
    • No need to worry about indexing or substring lengths.
  • Cons:
    • May require more memory allocations and deallocations due to the creation of intermediate arrays.
    • May be slower if the input string is very large, as it involves multiple iterations over the split strings.
• "Substring"`
  • Pros:
    • More efficient in terms of memory usage, as only a single substring is extracted.
    • Can be faster for large input strings, as it avoids the overhead of creating intermediate arrays.
  • Cons:
    • Requires careful tuning of indexing values to ensure accurate date component extraction.
    • May be harder to read and understand due to the use of substrings.

Library/Language Features

There is no explicit library or language feature being used in this benchmark. However, it's worth noting that the split() method is a built-in JavaScript method that splits a string into an array of substrings based on a specified delimiter.

Special JS Feature/Syntax

There are no special JavaScript features or syntax being tested in this benchmark. The focus is solely on comparing two basic string manipulation approaches: split() and substr().