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URL Origin: startsWith vs Regex various
(version: 3)
Comparing performance of:
Regular Expression vs StartsWith
Created:
4 years ago
by:
Registered User
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Tests:
Regular Expression
const https = 'https://www.example.com'; const slash = '//www.example.com'; const www = 'www.example.com'; /^(?:https?:)?\/\/(?:www\.)?/.test(https); /^(?:https?:)?\/\/(?:www\.)?/.test(slash); /^(?:https?:)?\/\/(?:www\.)?/.test(www);
StartsWith
const https = 'https://www.example.com'; const slash = '//www.example.com'; const www = 'www.example.com'; if(https.startsWith('http') || https.startsWith('//') || https.startsWith('www.')) return null; if(slash.startsWith('http') || slash.startsWith('//') || slash.startsWith('www.')) return null; if(www.startsWith('http') || www.startsWith('//') || www.startsWith('www.'))return null;
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
Regular Expression
StartsWith
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
one year ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36
Browser/OS:
Chrome 130 on Windows
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<iframe src="https://measurethat.net/Embed?id=566658" width="100%" height="500px"></iframe>
Test name
Executions per second
Regular Expression
20280320.0 Ops/sec
StartsWith
103737512.0 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Overview of the Benchmark** MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks to compare the performance of different approaches for various use cases. In this case, we have two individual test cases: "Regular Expression" and "StartsWith". We will analyze these test cases and explain what options are compared, their pros and cons, and other considerations. **Test Case 1: Regular Expression** The benchmark definition for the "Regular Expression" test case is: ```javascript /^(?:https?:)?\/\/(?:www\.)?/.test(https);\r\n/^(?:https?:)?\/\/(?:www\.)?/.test(slash);\r\n/^(?:https?:)?\/\/(?:www\.)?/.test(www); ``` This test case uses a regular expression to match three different URLs (`https`, `slash`, and `www`) against the pattern `/^(?:https?:)?\/\,(?:www\.)?/`. The goal is to determine which URL matches this pattern. **Regular Expression Options** There are two main options being compared in this test case: 1. **Regex Pattern**: The first option is the regex pattern itself, which is a fixed string: `/^(?:https?:)?\/\,(?:www\.)?/`. 2. **Regex Engine**: The second option is the JavaScript engine that executes the regular expression, such as V8 (used by Chrome). **Pros and Cons** * Pros of using a regular expression: + Can be more efficient for matching specific patterns. + Can be easily extended or modified to match new patterns. * Cons of using a regular expression: + Can be slower than other approaches due to the overhead of parsing and executing the regex pattern. + May not perform well on very large datasets. **Test Case 2: StartsWith** The benchmark definition for the "StartsWith" test case is: ```javascript if(https.startsWith('http') || https.startsWith('//') || https.startsWith('www.')) return null; if(slash.startsWith('http') || slash.startsWith('//') || slash.startsWith('www.')) return null; if(www.startsWith('http') || www.startsWith('//') || www.startsWith('www.'))return null; ``` This test case uses the `startsWith` method to check if each URL starts with a specific string. **StartsWith Options** There are two main options being compared in this test case: 1. **String Comparison**: The first option is the simple string comparison using the `startsWith` method. 2. **Regex Pattern**: The second option is the same regex pattern used in the "Regular Expression" test case, but used with the `startsWith` method. **Pros and Cons** * Pros of using `startsWith`: + Typically faster than regular expressions due to the simplicity of the comparison. + Can be more efficient for matching specific prefixes. * Cons of using `startsWith`: + May not perform well on very large datasets or complex patterns. **Other Considerations** In both test cases, the performance difference between the two options (Regex Pattern vs. String Comparison) is likely due to the overhead of parsing and executing the regex pattern. However, in certain scenarios, regular expressions may be necessary for matching complex patterns. It's also worth noting that the use of `startsWith` with string comparison can be more efficient than using a regex pattern, especially when only checking for simple prefixes. **Alternatives** Other alternatives to compare performance include: * Using a library like `regex-ast` or `fast-regex` which can optimize regex execution. * Using a different JavaScript engine or compiler, such as SpiderMonkey (used by Firefox). * Using a different programming language or framework, such as Python or Node.js. I hope this explanation helps!
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