Benchmark: getCookie string vs regex

Script Preparation code:

function getCookie(name) {
  var nameEQ = name + "=";
  var ca = document.cookie.split(";");
  for (var i = 0; i < ca.length; i++) {
    var c = ca[i];
    while (c.charAt(0) == " ") c = c.substring(1, c.length);
    if (c.indexOf(nameEQ) == 0) {
      var d = c.substring(nameEQ.length, c.length);
      d = decodeURIComponent(d);
      return d;
    }
  }
  return undefined;
}

function getCookieM(name) {
  name = name + "";
  var re = new RegExp("(^| )" + name + "=([^;]+)", "gmi");
  var m = document.cookie.match(re) || undefined;
  if (!!m) {
    m = m.pop();
    m = m.substring(m.indexOf("=")+1);
    m =  !!m ? decodeURIComponent(m) : m;
  }
   return m;
}

document.cookie = "foo=bar";
document.cookie = "foo=nope;domain=measurethat.net";

Tests:

String
getCookie('foo')
Regex
getCookieM('foo')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
String
Regex

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36

Browser/OS: Chrome 130 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
String	993224.4 Ops/sec
Regex	763294.8 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):

LLMs can make mistakes. Check important info.

The benchmark described in the provided JSON compares two different approaches for retrieving a cookie value from the `document.cookie` string in a web browser: a string-based method (`getCookie`) and a regex-based method (`getCookieM`).

### Options Compared

1. **String Method (`getCookie`)**
   - This method retrieves the value of a specified cookie by first preparing the cookie name in a format that allows it to match in the `document.cookie` string. It splits the cookie string into individual cookie components and iteratively checks each one until it finds a match. Once found, it extracts and decodes the cookie’s value.

2. **Regex Method (`getCookieM`)**
   - This method uses a regular expression to match the cookie name directly from the `document.cookie` string. It constructs a regex pattern to search for the cookie name and its corresponding value. If found, it captures the value and decodes it.

### Pros and Cons

- **String Method Pros:**
  - Simple and straightforward implementation; easy to understand for those new to JavaScript.
  - Does not require additional processing overhead from regex, which can be perceived as more cryptic.
  
- **String Method Cons:**
  - Potentially slower for large cookie strings since it involves iteration over each cookie.
  - May not be as flexible when matching patterns or complicated tokenization.

- **Regex Method Pros:**
  - More concise for matching cookie values, especially if there are multiple patterns needed for different cookies in one go.
  - Can be faster for large cookie strings as regex engines are highly optimized for pattern matching.

- **Regex Method Cons:**
  - Regular expressions can become complex and hard to read, particularly for those who aren’t familiar with regex syntax.
  - Overhead of regex parsing and execution may reduce performance for small cookie strings, leading to potentially less efficiency in simpler scenarios.

### Other Considerations

- **Performance:** Based on benchmark results, the string method executed slightly faster (1,052,448 executions per second) compared to the regex method (1,040,540 executions per second). This demonstrates that for this specific use case, the string method is marginally more efficient.
  
- **Maintainability:** While regex can provide powerful pattern matching capabilities, the added complexity in the code can make maintenance difficult. The string method might be preferable in situations where clarity and ease of maintenance are prioritized over minor performance gains.

### Libraries or Special Features

In this benchmark, no external libraries are used, and no special JavaScript features or syntax are leveraged beyond conventional string manipulation and regex.

### Alternatives

- **Using Object-Based Access:** Another alternative is to parse `document.cookie` into an object on initial load and access cookies via object keys thereafter. This would improve retrieval speed as parsing is done once, but it requires implementing an initial setup step.
  
- **Cookies API (with `js-cookie` or other libraries):** Utilizing libraries such as `js-cookie` provides a more robust cookie management solution, simplifying the process of setting, getting, and removing cookies without having to directly handle the `document.cookie` string.

- **Local Storage:** For data that doesn't need to expire at specific times (as cookies do), consider using `localStorage` or `sessionStorage`, which provide a simpler API for storing key-value pairs and aren't subjected to the size limitations and additional complexity inherent to cookie handling.

In summary, while both methods show merit, the string-based method in this case has proven slightly faster. As with many programming decisions, the best choice often depends on the specific context and goals of the application.

Related benchmarks:

getCookie string vs regex (version: 0)

Comparing performance of: String vs Regex

Created: 2 months ago by: Guest

Jump to the latest result

String

Regex

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):