Benchmark: Benchmark getting file extension

Script Preparation code:

var fileName = "test.jpg"
var regex = /\.[^\.]+$/;

Tests:

match
const fileExtension = fileName?.match(/\.[^\.]+$/)?.[0]
split & pop
const fileExtension = `.${fileName?.split('.').pop()}`;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
match
split & pop

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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Let's break down the benchmark definition and test cases to understand what is being tested.

**Benchmark Definition**

The benchmark measures the performance of two different approaches to get the file extension from a file name. The script preparation code provides the initial setup for the benchmark:

```javascript
var fileName = "test.jpg";
var regex = /\\.[^\\.]+$/;
```

Here, `fileName` is set to `"test.jpg"` and a regular expression `regex` is defined to match the file extension. The `^` character at the start of the regular expression is a special character that matches the beginning of a string.

**Test Cases**

There are two test cases:

1. **"match"**
```javascript
const fileExtension = fileName?.match(/\\.[^\\.]+$/)?.[0];
```

This approach uses the `match()` method to search for the first occurrence of the regular expression in the `fileName` variable. The `?.` operator is called the "optional chaining operator", which allows us to access nested properties or methods if they exist. In this case, it's used to avoid null pointer exceptions.

The `[0]` at the end of the expression returns the first captured group (the file extension) from the match result.

Pros:

* Simple and concise syntax
* Works with non-strict modes

Cons:

* Can be slower due to the overhead of regular expressions
* May not work as expected if `fileName` is null or undefined

2. **"split & pop"**
```javascript
const fileExtension = `.${fileName?.split('.').pop()}`;
```

This approach uses the `split()` method to split the `fileName` variable into an array of substrings, and then takes the last element (`pop()` returns the last item in the array) followed by a dot (`.`).

Pros:

* Can be faster than regular expressions
* Works even if `fileName` is null or undefined (will return an empty string)

Cons:

* More verbose syntax compared to the "match" approach
* May not work as expected if `fileName` has multiple '.' characters

**Library Usage**

There are no libraries used in these test cases.

**Special JS Features/Syntax**

The optional chaining operator (`?.`) is a relatively new feature introduced in JavaScript (ECMAScript 2020) to safely navigate nested properties or methods. It's available in modern browsers and engines, but not in older ones.

**Other Alternatives**

If you need to get the file extension from a file name, other alternatives might include:

* Using `fileName.split('.').pop()` without an optional chaining operator (as shown in the "split & pop" approach)
* Using `fileName.replace(/^.*\./, '')` to remove everything before the last '.' character
* Using a library like `path` or `fs` if you're working with Node.js and need to handle file paths

Overall, the choice of approach depends on your specific use case, performance requirements, and personal preference.

Related benchmarks:

Benchmark getting file extension (version: 0)

Comparing performance of: match vs split & pop

Created: 4 years ago by: Guest

Jump to the latest result

match

split & pop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):