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substr vs startsWith
(version: 0)
Benchmark.js
test perf of substr vs startsWith
Comparing performance of:
substr vs startsWith
Created:
8 years ago
by:
Guest
Go to the latest result
Script Preparation code:
var str = "abcdefghijklmnopqrstuvwxyz";
Tests:
substr
return str.substr(0,10) == 'abcdefghij'
startsWith
return str.startsWith('abcdefghij')
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
substr
startsWith
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
7 months ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:147.0) Gecko/20100101 Firefox/147.0
Browser/OS:
Firefox 147 on Windows
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=624306" width="100%" height="500px"></iframe>
startsWith
590.4M/s
substr
579.0M/s
View exact numbers
Test name
Executions per second
✓
startsWith
590,398,400 Ops/sec
substr
578,967,616 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided JSON and explain what is being tested, compared options, pros and cons, library usage, special JS features, and other considerations. **Benchmark Definition** The benchmark is defined in two test cases: 1. `substr`: Tests the performance of using the `substr` method to extract a substring from the string `str`. 2. `startsWith`: Tests the performance of using the `startsWith` method to check if the string starts with a specified substring. **Options Compared** In both test cases, the options being compared are: * Using `substr` vs. using `startsWith`. **Pros and Cons of Each Approach** 1. **Using `substr`:** * Pros: + More flexible, as it allows you to extract any part of the string. + Can be used for more complex substring matching tasks. * Cons: + May require more overhead due to the need to calculate the start index. 2. **Using `startsWith`:** + Pros: + Generally faster and more lightweight, as it only checks if a prefix exists. + More efficient in terms of execution speed. + Cons: + Less flexible than `substr`, as it can only check for exact prefixes. **Library Usage** There is no explicit library usage mentioned in the JSON. However, JavaScript's built-in string methods, including `substr` and `startsWith`, are used. **Special JS Features or Syntax** There are no special JavaScript features or syntax used in this benchmark that would require explanation. **Other Considerations** When choosing between `substr` and `startsWith`, consider the specific requirements of your use case. If you need to extract a specific substring, `substr` might be a better choice. However, if you only need to check for an exact prefix, `startsWith` is likely faster and more efficient. **Alternatives** Other alternatives to `substr` and `startsWith` include: * Using a regular expression to achieve similar results. * Implementing custom substring or prefix checking logic using bitwise operators or other techniques. * Using a library like Lodash, which provides additional string manipulation methods. Keep in mind that the choice of method depends on your specific use case and performance requirements.
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