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leftPadtest
(version: 0)
Benchmark.js
Comparing performance of:
leftpad1 vs leftpad2 vs primeagen
Created:
2 years ago
by:
Guest
Go to the latest result
Tests:
leftpad1
function leftpad1(str, len, ch){ return (ch + str).slice(-len) }
leftpad2
function leftpad0(str, len, ch) { str = String(str); var i = -1; if (!ch && ch !== 0) ch = " "; len = len - str.length; while (++i < len) { str = ch + str; } return str; }
primeagen
function leftpad3(str, len, ch) { return new Array(len - str.length).join(!ch && ch !== 0 ? " " : ch) + str; }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
leftpad1
leftpad2
primeagen
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
2 years ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36
Browser/OS:
Chrome 120 on Windows
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=493914" width="100%" height="500px"></iframe>
leftpad2
990.0M/s
primeagen
962.0M/s
leftpad1
918.7M/s
View exact numbers
Test name
Executions per second
✓
leftpad2
990,028,480 Ops/sec
primeagen
962,038,912 Ops/sec
leftpad1
918,665,856 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided JSON and explain what's being tested, compared, and other considerations. **Benchmark Definition** The benchmark definition is missing in the provided JSON. It should contain information about the test case, such as the function name, input parameters, and expected output. **Individual Test Cases** There are three test cases: 1. `leftpad1` * Benchmark Definition: This function takes a string (`str`), a length (`len`), and a character (`ch`) as inputs. It returns the left-padded string by concatenating the character to the right of the original string using the `slice()` method. 2. `leftpad0` * Benchmark Definition: This function is similar to `leftpad1`, but it uses a different approach: + Converts the input string to a primitive value (`str = String(str)`). + Initializes an index variable (`i`) and checks if the character is null or zero (`ch`). + Calculates the length of padding required by subtracting the original string's length from the desired length. + Loops through the padding characters, concatenating them to the left of the original string using `ch + str`. 3. `primeagen` * Benchmark Definition: This function is not a standard JavaScript function and appears to be unrelated to the left-padding test case. **Comparison** The benchmark tests different approaches for left-padding: 1. **`leftpad1`**: Uses the `slice()` method, which creates a new string by extracting a subset of characters from an existing string. 2. **`leftpad0`**: Uses a loop to concatenate padding characters to the original string. **Pros and Cons** * `leftpad1`: + Pros: Efficient use of `slice()`, concise code. + Cons: May not be suitable for large strings due to memory allocation overhead. * `leftpad0`: + Pros: More explicit control over padding, handles edge cases (null or zero character). + Cons: Longer code, more verbose. **Library** None of the test cases use a standard JavaScript library. However, `String()` is used in `leftpad0`, which is a built-in function. **Special JS Features/Syntax** None of the test cases explicitly utilize special JavaScript features or syntax (e.g., async/await, arrow functions). **Alternatives** For left-padding, other approaches could include: 1. Using string interpolation methods like `String.prototype.padStart()` (if supported by the browser). 2. Utilizing string manipulation libraries like `lodash`. 3. Implementing a custom padding algorithm using bitwise operations or regular expressions. In summary, the benchmark tests three different approaches for left-padding: `leftpad1` uses `slice()`, `leftpad0` uses a loop, and `primeagen` is not a standard JavaScript function. The pros and cons of each approach highlight the trade-offs between efficiency, conciseness, and explicit control in coding.
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