Benchmark: startsWith vs regex hash

Tests:

regex
/^#/.test('#/abs')
startsWith
'#/abs'.startsWith('#')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regex
startsWith

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36 Edg/141.0.0.0

Browser/OS: Chrome 141 on Windows

View result in a separate tab

Test name	Executions per second
regex	71995800.0 Ops/sec
startsWith	201619888.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview**

The provided JSON represents a JavaScript microbenchmarking test case on the MeasureThat.net website. The test compares two approaches: using a regular expression (regex) to check if a string starts with a specific prefix, and using the `startsWith()` method.

**Options being compared**

Two options are being compared:

1. **Regex**: Using a regex to check if a string starts with a specific prefix (`"/^#/.test('#/abs')"`).
2. **startsWith() method**: Using the `startsWith()` method of JavaScript strings to check if a string starts with a specific prefix (`"'#/abs'.startsWith('#')"`).

**Pros and Cons**

Here's a brief overview of each approach:

### Regex

Pros:

* Flexibility: regex can be used for more complex pattern matching, not just simple string prefix checks.
* Performance: in some cases, regex might be optimized to perform better than the `startsWith()` method.

Cons:

* Complexity: writing and maintaining regex patterns can be error-prone and time-consuming.
* Overhead: regex operations can have additional overhead due to parsing and compilation.

### startsWith() method

Pros:

* Simplicity: using `startsWith()` is often more straightforward and easier to understand than regex.
* Native performance: the `startsWith()` method is a native JavaScript function, which means it's likely optimized for performance.

Cons:

* Limited flexibility: `startsWith()` only checks if the string starts with a specific prefix; it doesn't support more complex pattern matching.

**Library**

None of the test cases use any external libraries. The regex patterns are built-in to JavaScript, and the `startsWith()` method is also a native function.

**Special JS feature or syntax**

The test case uses a special feature of modern JavaScript: template literals (`''`).

**Benchmark result**

The latest benchmark results show that the `startsWith()` method outperforms the regex approach in this specific test case. This is likely due to the optimized performance of the `startsWith()` method and the additional overhead introduced by the regex pattern.

**Other alternatives**

If you're looking for alternative approaches, here are a few options:

* **Substring()**: You can use the `substring()` method to extract the prefix from the string and then compare it.
* **indexOf()**: The `indexOf()` method returns the index of the first occurrence of the prefix in the string. You can use this to implement your own prefix check.

However, these alternatives might not be as efficient or straightforward as using the `startsWith()` method.

In conclusion, the test case compares two simple approaches: using regex and using the `startsWith()` method. The results suggest that the `startsWith()` method is a better choice for this specific use case due to its optimized performance and simplicity.

Related benchmarks:

startsWith vs regex hash (version: 0)

Comparing performance of: regex vs startsWith

Created: 2 years ago by: Guest

Jump to the latest result

regex

startsWith

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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