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String start with 1st char
(version: 0)
Comparing performance of:
String.startsWith vs Compare by 1st char
Created:
2 years ago
by:
Registered User
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HTML Preparation code:
<input />
Script Preparation code:
window.names = ["$item1", "someval", "someVal2", "$someVal3"]
Tests:
String.startsWith
names.filter(n=>n.startsWith("$"));
Compare by 1st char
names.filter(n=>n[0]==="$");
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
String.startsWith
Compare by 1st char
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'll break down the benchmark and explain what's being tested, compared, and discussed. **Benchmark Overview** The benchmark measures the performance of two different approaches to filtering an array of strings: one using the `startsWith` method and the other by comparing the first character of each string to a predefined value (`$`). **Script Preparation Code** The script preparation code sets up the input data: ```javascript window.names = ["$item1", "someval", "someVal2", "$someVal3"]; ``` This creates an array `names` containing four strings, which will be used for filtering. **Html Preparation Code** The HTML preparation code is empty, indicating that no specific HTML structure needs to be created or modified for the benchmark. **Individual Test Cases** There are two test cases: 1. **"String.startsWith"`** This test case filters the `names` array using the `startsWith` method: ```javascript names.filter(n => n.startsWith("$")); ``` The `startsWith` method checks if the first character of each string matches the specified value (`$`). This approach is simple and straightforward. 2. **"Compare by 1st char"`** This test case filters the `names` array by comparing the first character of each string to `$`: ```javascript names.filter(n => n[0] == "$"); ``` Instead of using the `startsWith` method, this approach uses indexing (`n[0]`) to access the first character of each string and compares it to `$`. This approach is also simple but may be less efficient than using the `startsWith` method. **Pros and Cons** **"String.startsWith"`** Pros: * More readable and maintainable code * Less prone to errors due to indexing issues Cons: * May have slower performance compared to direct character comparison (as seen in the "Compare by 1st char" test case) **"Compare by 1st char"`** Pros: * Can be faster for small datasets or strings with few characters * May be optimized by the JavaScript engine Cons: * More error-prone due to indexing issues * Less readable and maintainable code **Library: `filter()`** The `filter()` method is a built-in JavaScript array method that creates a new array containing all elements that pass the test implemented by the provided function. In both test cases, `filter()` is used to create a new array with filtered strings. This approach is efficient and widely supported across browsers. **Special JS Feature/Syntax: `$`** The `$` symbol is a reserved character in JavaScript that represents the start of a template literal. However, it's also being used as a string prefix in this benchmark. The use of `$` in this context doesn't have any specific meaning or feature, and it's simply a placeholder for demonstration purposes. **Other Alternatives** Some alternative approaches to filtering an array of strings could include: * Using `Array.prototype.reduce()` with an initial value of 0 * Utilizing a library like Lodash (e.g., `_filter()`) * Implementing a custom filtering function using regular expressions However, these alternatives are not being tested in this benchmark, and the focus is on comparing the performance of two simple approaches: `startsWith` and direct character comparison.
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