Let's dive into the world of MeasureThat.net and explore what's being tested in this benchmark.

Benchmark Definition

The benchmark is designed to test two approaches for validating three-digit strings: using regular expressions (Regex) and looping through each character.

Script Preparation Code

Both test cases start with the same preparation code:

var string = "abe123";

This sets a predefined input string string that will be used as the test subject for both approaches.

Benchmark Definition Details

Now, let's analyze the two benchmark definitions:

1. Regex Benchmark The first test case uses regular expressions to validate if the last three characters of the string are digits:

let isLastNameValid = false;
const THREE_DIGIT_REGEXP = /\\d{3,}/;
isLastNameValid = THREE_DIGIT_REGEXP.test(string);

This approach relies on a predefined regular expression pattern (\\d{3,}) to match three or more consecutive digits at the end of the string.

Pros and Cons

Advantages:

• Concise and expressive code
• Easy to read and maintain

Disadvantages:

• May not work as expected for edge cases (e.g., non-numeric characters before the digit sequence)
• Performance may vary depending on the regex engine used by the browser

2. Loop Benchmark The second test case uses a manual loop to iterate through each character of the string and count the digits:

let isLastNameValid = false;
let digits = 0;
for (let i = 0; i < string.length; i++) {
  !isNaN(string.charAt(i)) && digits++;
}
isLastNameValid = digits >= 3;

This approach involves a simple loop that checks each character of the string using the isNaN() function to detect numeric characters.

Pros and Cons

Advantages:

• Works for edge cases (e.g., non-numeric characters before the digit sequence)
• Easy to understand and implement

Disadvantages:

• More code than the Regex approach
• Performance may be slower due to the loop overhead

Library: THREE_DIGIT_REGEXP

The THREE_DIGIT_REGEXP variable is a predefined regular expression pattern that is used in the Regex benchmark. This pattern is likely defined by MeasureThat.net to provide a consistent and efficient way to match three or more consecutive digits at the end of a string.

Special JavaScript Feature/Syntax: None

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

Other Alternatives

If you were to rewrite this benchmark, you could consider alternative approaches, such as:

• Using a more complex regular expression pattern to match three-digit strings with optional leading characters (e.g., \\d{3}(?:[0-9]*[0-9])?)
• Using a different algorithm, such as a greedy approach that tries to find the first sequence of digits and then checks if it's at least three characters long.

Keep in mind that these alternatives might affect performance or accuracy, so it's essential to test and validate them thoroughly.