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charCodeAt vs charAt
(version: 0)
Benchmark.js
Comparing performance of:
charAt vs charCodeAt vs use []
Created:
4 years ago
by:
Registered User
Go to the latest result
Script Preparation code:
var a = "abcdefghijklmnopqrstuvwxyz" var b = "x" var c = b.charCodeAt(0)
Tests:
charAt
for(let i = 0; i < a.length; ++i) { if(a.charAt(i) == b) break; }
charCodeAt
for(let i = 0; i < a.length; ++i) { if(a.charCodeAt(i) == c) break; }
use []
for(let i = 0; i < a.length; ++i) { if(a[i] == b) break; }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
charAt
charCodeAt
use []
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
5 days ago
)
User agent:
Mozilla/5.0 (iPhone; CPU iPhone OS 26_6_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/152.0.7977.112 Mobile/15E148 Safari/604.1
Browser/OS:
Chrome Mobile iOS 152 on iOS 26.6.1
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=634052" width="100%" height="500px"></iframe>
charCodeAt
64.4M/s
use []
41.2M/s
charAt
21.8M/s
View exact numbers
Test name
Executions per second
✓
charCodeAt
64,355,564 Ops/sec
use []
41,165,004 Ops/sec
charAt
21,755,770 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark and its various components. **Benchmark Definition** The benchmark definition is a JSON object that describes the test case. In this case, it's a simple comparison between three different approaches: 1. `charAt`: Uses the `charAt()` method to get the character at a specific index in a string. 2. `charCodeAt`: Uses the `charCodeAt()` method to get the Unicode code point of a character at a specific index in a string. 3. `use []`: Uses array indexing (`a[i]`) to access characters in the string. **Options Compared** The three options are being compared to see which one is faster for this specific test case. The test case is designed to measure the performance difference between these three approaches. **Pros and Cons of Each Approach:** 1. `charAt`: * Pros: Simple and straightforward, easy to understand. * Cons: May have a lower performance due to its nature (it's an array lookup). 2. `charCodeAt`: * Pros: Can provide more information about the character (its Unicode code point), but it may also incur additional overhead due to the conversion process. * Cons: May be slower than direct indexing, as it involves a function call and a lookup in an internal table. 3. `use []`: * Pros: Can be faster than direct indexing since array indices are typically optimized for performance. * Cons: Requires explicit indexing of the string, which can be less intuitive and less readable. **Library Used** There is no explicit library mentioned in the benchmark definition, but it's likely that JavaScript's built-in string methods (like `charAt()` and `charCodeAt()`) are being used. The `use []` option assumes that the string is an array-like object where indexing can be used to access characters. **Special JS Feature/Syntax** There are no special features or syntaxes mentioned in this benchmark definition, as it's a straightforward comparison of three simple methods. However, if we were to consider more advanced JavaScript features, some examples could include: * ES6 template literals (for string interpolation) * String manipulation functions like `replace()` or `split()` * Regular expressions for pattern matching **Other Alternatives** If the benchmark were being run in a different context, other alternatives might be considered, such as: * Using a library specifically designed for performance optimization, like V8's own optimizer * Implementing a custom string manipulation algorithm optimized for specific use cases * Compiling JavaScript code to native machine code (although this is typically not recommended due to its complexity and potential security risks) For the given benchmark definition, the `use []` approach would likely provide the best performance, as it eliminates the overhead of function calls and array lookups. However, readability and maintainability should be considered when choosing an optimization strategy in a real-world scenario.
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