Toggle navigation
MeasureThat
.net
Create a benchmark
Tools
Feedback
FAQ
Register
Log In
starts with vs regex
(version: 1)
Comparing performance of:
startsWith vs regex
Created:
one year ago
by:
Guest
Go to the latest result
HTML Preparation code:
<!--your preparation HTML code goes here-->
Script Preparation code:
let regex = /^abc.*$/
Tests:
startsWith
'abc123'.startsWith('abc')
regex
regex.test('abc123')
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
Fork
Test case name
Result
startsWith
regex
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
one month ago
)
User agent:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:152.0) Gecko/20100101 Firefox/152.0
Browser/OS:
Firefox 152 on Mac OS X 10.15
View result in a separate tab
Embed
Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=629638" width="100%" height="500px"></iframe>
startsWith
1575.8M/s
regex
62.2M/s
View exact numbers
Test name
Executions per second
✓
startsWith
1,575,830,656 Ops/sec
regex
62,186,144 Ops/sec
Autogenerated LLM Summary
(model
gpt-4o-mini
, generated one year ago):
The benchmark defined in the provided JSON measures the performance of two different approaches for checking whether a string starts with a specific substring: using the `startsWith()` method and using a regular expression (`regex`). ### Options Compared 1. **`startsWith()` Method**: - **Test Case**: `'abc123'.startsWith('abc')` - **Purpose**: This method is a straightforward way to check if a string begins with a specified substring. It takes one argument (the substring) and returns a boolean value (`true` or `false`). 2. **Regular Expression**: - **Test Case**: `regex.test('abc123')` - **Purpose**: This approach uses a regular expression to achieve the same goal. The regex pattern defined in the preparation code, `let regex = /^abc.*$/`, matches any string that starts with 'abc'. The `test` method of the regex returns `true` or `false` depending on whether there's a match. ### Pros and Cons #### `startsWith()` Method - **Pros**: - Clear and concise: The intent is immediately understandable. - Performance: Typically optimized for speed in most modern JavaScript engines. - Readability: Easier to read and maintain, especially for developers who may not be familiar with regular expressions. - **Cons**: - Less flexible: It can only check static substrings and does not support complex patterns or conditions. #### Regular Expression - **Pros**: - Flexibility: Regular expressions can match complex patterns, allowing for more sophisticated validation. - Power: Can be very powerful for pattern matching beyond simple substring scenarios. - **Cons**: - Performance: Generally slower than direct string methods, especially for simple checks, as regex engines need to interpret the pattern. - Complexity: Might be less readable for those unfamiliar with regex syntax, leading to potential maintenance issues. ### Other Considerations - **Readability vs Performance**: In scenarios demanding high performance with simple checks, `startsWith()` is often the preferred choice due to its clarity and speed. Conversely, when matching complex string patterns or rules, regex is indispensable despite the potential performance cost. - **Library and Syntax**: No external libraries are used here, and the syntax is pure JavaScript. The benchmark operates directly in the JavaScript environment, making use of standard language features. ### Alternatives While these two methods are commonly used for the specific task of checking string prefixes, other alternatives might include: - **`indexOf()` Method**: `abc123`.indexOf('abc') === 0` could achieve a similar result by checking if the substring starts at index `0`. However, it lacks the semantic clarity of `startsWith()`. - **String Slicing**: Another approach could involve comparing the sliced portion of the string: `'abc123'.substring(0, 3) === 'abc'`. This is less efficient and readable compared to `startsWith()`. In summary, this benchmark provides critical insights into the performance differences between two approaches, helping developers make informed choices based on the specific requirements of their applications.
Related benchmarks
RegEx.test vs String.search
RegEx.test() vs String.search()
My Slice vs Regex
Regex type checking comparison
endsWith vs Regex2
Comments
Confirm delete:
Do you really want to delete benchmark?