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leftPad vs nativeLeftPad
(version: 0)
Benchmark.js
Comparing performance of:
nativeLeftPad vs leftPad
Created:
3 years ago
by:
Registered User
Go to the latest result
Tests:
nativeLeftPad
function nativeLeftPad(string, len, ch) { return string.padStart(len, ch); } nativeLeftPad('abcdefg', 10, '0')
leftPad
function leftPad(str, len, ch) { let new_str = `${ch.repeat(len)}${str}`; return new_str.slice(-len); } leftPad('abcdefg', 10, '0')
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
nativeLeftPad
leftPad
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=493915" width="100%" height="500px"></iframe>
nativeLeftPad
10.8M/s
leftPad
8.9M/s
View exact numbers
Test name
Executions per second
✓
nativeLeftPad
10,811,108 Ops/sec
leftPad
8,941,133 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark and explain what's being tested. **Benchmark Definition** The benchmark definition is a JSON object that describes two JavaScript functions: `nativeLeftPad` and `leftPad`. The purpose of these functions is to pad a given string with a specified character (or characters) to achieve a certain length. **Options Being Compared** The two options being compared are: 1. **Native `padStart()` method**: This is a built-in JavaScript method that pads a string with a specified character (or characters) on the left until it reaches a specified length. 2. **Custom `leftPad()` function**: This function takes three arguments: the input string, the desired padding length, and the character(s) to use for padding. **Pros and Cons** Here are some pros and cons of each approach: **Native `padStart()` method** Pros: * Efficient: Built-in methods like `padStart()` are optimized for performance. * Portable: Works across different browsers and environments without modifications. Cons: * Limited control: The resulting string is always padded with the same character(s) on the left. * Potential security risks: If used with untrusted input, this method can lead to injection vulnerabilities. **Custom `leftPad()` function** Pros: * Customizable: Allows for more control over the padding process and potential for optimization. * Secure: By explicitly choosing the padding characters, you can mitigate security risks associated with untrusted input. Cons: * Inefficient: Implementing a custom solution can lead to slower performance compared to built-in methods. * Less portable: Requires modifications to work across different browsers and environments. **Other Considerations** When designing or using these functions, consider the following factors: * Input validation: Ensure that input strings are properly sanitized and validated to prevent security risks. * Padding character selection: Choose padding characters carefully to achieve the desired effect while minimizing potential issues (e.g., null or undefined characters). **Library Usage** Neither of the provided functions uses any external libraries. The `padStart()` method is a built-in JavaScript function, while the custom `leftPad()` function does not rely on any third-party libraries. **Special JS Features/Syntax** There are no special JavaScript features or syntax used in these benchmarks. They only employ basic string manipulation and control flow constructs (if/else statements). Now that we've dissected the benchmark, here are some alternative approaches you could consider: 1. **Using `toString()` with a padding string**: You can use the `toString()` method to concatenate the input string with a padding string of desired length. This approach provides more control over the padding process but may be less efficient than using `padStart()`. 2. **Employing string interpolation**: String interpolation techniques, like template literals (`${}`), could be used to create a padded string. However, this might not be as straightforward or performance-friendly as using built-in methods. 3. **Exploring other padding methods**: Depending on your specific requirements, you may need to explore alternative padding methods, such as using `Array.prototype.fill()` or working with buffer types. These alternatives can help you better understand the strengths and weaknesses of different approaches when implementing string padding in JavaScript.
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